Oh dear, poor you Lisa. Your lil boy is struggling and not doing very well. Something somewhere seems to have damaged him, maybe in the forces - does he speak positively of that period? Maybe something before that. I think you're wrong when you say, 'he has no regard for my feelings'. From what you say, his attitude towards you is indicative of a lad that's hurting and wants to share that hurt by hurting the one that's closest to him: you. Is drugs still a part of his life? If it is, that's your problem. Either way I suggest you regularly reach out to him by chatting, email, SMS or a short letter, letting him know that you're there willing him better, reaching out wanting to help and together work out and untangle the mess. Let him know that you're praying for him and go into some detail about your prayer, rather than a glib 'I'm praying for you'. Do that and expect to be rebutted and hurt more but be strong and don't give in or give up. Eventually his eyes will open and he'll see just what a balloon he's been.
Meanwhile, focus also on yourself. You need to be v strong so rebuild your strength. Work on your own faith with lots of prayer, meditation and Bible reading. Talk to God and ask Him through His Holy Spirit to give you the strength to get through this awful period. Do share and ask for prayer support in your church. Most of all focus on your faith, give it to God and ask Him to give you wisdom and strength to get through.
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Dear Lord God, I pray for Lisa, It's heartbreaking to read about a sister of mine being hurt like this. Please give her your strength to cope and get through this awful period that she's going through in her life. Please Lord work in her through your Holy Spirit giving her your peace and reassurance that ultimately you're in control of this test in her faith; give her the wisdom and your strength to get through this Lord. Please Lord, working through Lisa or whatever way you can please stir in her son a desire to resolve his issues rather than falling victim to them. I know he's can't solve them, that's your job Lord, but he needs to return to you in the same way as the prodigal son returned when he'd tired of pigswill. Please work with Lisa and her son to bring them back into your loving care.
AMEN