You fall, you pray, you get back up...you learn. I just don't want to lose my relationship with Christ (still developing, btw) or become hardened in my sins.
Please pray.
Hello dear friend. I'm sorry to see you going through this right now. I think the fact that you show such remorse over your sin shows your heart is not hardened because of your sin. One thing I do want to caution you about (something that I had to learn the hard way) is not to rationalize sin ("I fell because I was lonely"). By rationalizing sin through excuses we comfort ourselves. You are feeling the pain of the guilt of your sin (that guilt is something Holy and from God), but you are trying to comfort yourself by rationalizing why you committed your sin (unholy). Seek the Lord's comfort instead. God is good and while it is painful to stand convicted of sin before Him, our repentance through Christ, makes it possible to run into his arms for comfort.
If I may offer some gentle advice (you know my heart for you), I would suggest you ask the Holy Spirit to reveal to you the damage of rationalizing/excusing sin (or the why's of sin) and repent. It's certainly something to pray over, not just in this sin area, but in all sin areas. It will certainly keep your heart softened and tender before the Lord. I've learned to pray "God, I have no excuses, I sinned and I have nothing I can offer you to rectify my sin please forgive me or there is no hope for me, please change my heart." It's amazing the perspective you have when you learn to pray that prayer.
You say that you got lonely and it was one reason that tempted you to sin, now on the one hand I agree with you (like you said an ex-drug addict or alcoholic would go back to their drug and you went back to yours), that you were stressed out and triggered into acting like the "old natured" you. I feel that the Lord is exposing to you the healing you still need so you can grow in Him and overcome your past hurts. You see your loneliness that triggered you to seek the comfort of intimacy is simply the "fruit" of a much deeper problem. We simply can't ask for forgiveness and fight temptation, the enemy will eventually wear us out and we'll fall to sin again. This battle strategy that is good! (don't get me wrong) is not enough to win the war (the battle certainly). We need to be transformed through and in Christ by the renewing of our minds (Romans 12:2). The reason you fell to this sin again is because you simply chopped down the tree that produced this sinful fruit (sexual immorality) in your life, but since you didn't uproot this "tree" it grew back and began to produce fruit in your life once again. That is the nature of the weeds, if we don't pull them up by their roots, they simply come back.
You weren't simply driven by lust (the fruit), but by a deeper need of intimacy to comfort your soul* (perhaps, it was your spirit that wanted to be comforted through intimacy?) The real root cause is hidden to you right now. I believe the Lord is asking you to find out what the root is so that He can remove it. "Roots" of sin come in through brokenness/pain and are sinful in and of themselves. They are removed through being forgiven and through forgiving.
For example, a child is molested at the age of 5 (the root). This sin against the child creates brokenness in her and that pain can be manipulated by the devil to lead the child into sin. So, that 5 year old begins to believe the lies of the devil that they are worthless or disgusting or it's their fault (fruit). Then as an adult who understands God's laws, she decides to be promiscuous or do drugs (another example of fruit) to comfort the pain, but this time this girl is now responsible before God for her actions. She is sinfully reacting to express her pain. She needs to seek forgiveness from God for her sins (the fruit), and forgive the man who sinned against her (the root). Do you see the balance?
Through prayer, fasting, and seeking the Lord you can find the root of your pain so that you are no longer triggered into seeking unholy intimacy. What triggered you to seek this hookup? What was the thought process in your mind that was able to convince you to sin? What was the week or so before this sin like for you? These answers will be some major clues to help you identify the root of your sin. Use this "fall" to uproot all the unholy roots that allow you to sin so that you don't have to fall this way again. BTW- these questions are all rhetorical, no need to answer them in the open forum.
Also, I know it's not popular on this forum, and that's okay but I believe that sex bonds the spirits/souls of the participants because of the ministry work I've seen and done. If you don't believe in this particular teaching, it's more than okay. But, I would also suggest that you ask the Lord to break any unholy connection that was made between you and your partner. Sex is good and holy, within the parameters of God's mandates, and it is intended to bring a couple together and strengthen their spirits and souls. But, in the unholy context of sin, sex is destructive to the spirit and soul. Once again, if this is not something you personally believe, no problem. I simply bring it up in case you are open to this teaching.
Lastly, I also advise you to ask the Lord to begin to heal the damage done to your soul over all the years of sin that hurt you. You see, the soul (mind, will, emotions) is not bad or evil it simply needs to be retrained to mirror Christ. Sin damages our souls and we need to ask the Lord to heal our souls from our sin. (If you'd like to seek an example, PM me and I will give your examples from my personal life.) It is a painful process, I won't hide that from you, but the pain of healing our damaged souls is less than the pain of falling to sin. I would also suggest that one reason you were able to fall to sin, in the first place, is because your soul is not fully healed or recovered from the damage "old natured man" caused when he was alive in sin.
*The Bible teaches us that we have our own "spirit man" and we need to allow our spirits (who have been born again in Christ) to lead our souls (which need to be retrained, crucified daily, and transformed) instead of the other way around. It could very well be that your spirit man wanted to seek intimacy with the Father's heart, but your soul misinterpreted that desire and brought you into sin to satisfy that desire. Think about it this way, if I remember correctly doctors say that 90% of the time when we feel hungry we are actually thirsty! People misinterpret their desire and over eat and don't feel satisfied because their body simply want waters. Now, I don't know if this is the reality of what is happening in your spirit/soul. I am not trying to say that this is the root or reality of your situation. I'm simply throwing out questions to get your mind going in the Holy Spirit. Only the Lord God can reveal the root causes of your sin to you (there is most likely more than 1 root cause that tempts you into seeking unholy relationships).
I hope these things make sense to you, but if you need clarity just ask. You are free to reject any of my advice or words, I will not take offense. What matters most is you growing in Christ to be set free and walk in the fullness of His identity. You are a dear friend and I pray that God continues to heal you and make you a powerful living testimony of His power and grace.
God bless you, Christ_Empowered!
(PS: Identity is another major reason why we sin. We sin because we don't know who we are in Christ. I urge you, brother, to continue to seek the Lord's truth concerning your identity).