How can I make a relationship w him work?

He’s married but left his wife and 7-year-old for faraway job - says he just felt like it, for $/selfishness/ freedom, and his family cried for him to stay but he ignored. He’ll go back whenever vacation time allows, but it’s really far so that’s every few months. I said well something must have been wrong in your marriage, there was some reason you left, and he insists nothing at all. Says it’s unfair for me to ask anything of him while he’s missing his son but he’s the one who chose to leave and had plenty of opportunities to go back. In the meantime, while his move was pending, he asked his old GF to move w him instead, then went back on it. Says his wife briefly thew him out for that, & he sat down with the two of them together and said he loved both. Says his ex once tried to commit suicide bc of him, he wronged both women so badly. Confusing bc he’d say things in text like he really cared & felt close to me, but always in person was cold and detached/ like always left right after sex, if I ever put an affectionate hand on him he’d remove it, push my face away if I kissed him during sex. Valentine’s Day was first weekend I’d see him in months bc he’d been with his wife & son. But he never acknowledged it, randomly said he was going to Prague with a friend, and when I said i was bummed he says “well I always told you I could only do a casual relationship.” He had?!! Then went on about how he’s a failure and disappointment to everyone and I needed to give him time to see a therapist. But he never did, and then Just kept insisting we were only friends and never had been more. Initially led me to believe he’s getting divorced, but then went back on it for his son’s sake/ so he doesn’t need to give away $, and says he never wants to marry or commit to anyone again so what would it matter.  Said he’s too badly scarred to love again, and he doesn’t form attachments. Freaked out over 1 pic of us I posted and said he wouldnt be allowed to see his son. Hides me to point of not getting a ride to a mutual friend’s party w me. Says I’m special to him but there’d always be expectations he couldn’t meet and he will never be able to fully be w anyone. Told me repeatedly we would only ever be friends, but tried to make me feel badly for seeing other men and then I asked him about one girl liking all his social media. He said a bunch of elaborate stuff about how he wanted her and they were close in the past, then said he made it up to get me to move on, then she defriended / blocked him. Then suddenly he’s going to a party w her and bringing his son allegedly buT at very same time sexting me and making plans to meet up with me again for sex. I feel like he’s just afraid to love and I should help him feel more comfortable and accepted. But it stuck w me when he says if he could leave his son he’ll leave anyone. And thru it all, things have been heavily focused on sex, but he’ll randomly withdraw it bc he feels guilty since still married/doesn’t want it to have power over him, but even thru those times sexts me or asks me to do a sexual favor on occasion.

You need to sit down and try and list the good things about knowing this guy, if any. He's using you for sex but if that's all OK with you, then fine, but don't expect to have any sort of successful or fulfilling relationship with him because he has no respect for you whatsoever. The guy has to sort his marriage whether he realises it or not, and you don't need to be there to watch it. He's not doing it properly, instead he's dragging people like you into it, people who will get hurt, just as much as his wife and son will. A guy who can just blithely 'walk away' from his responsibilities is not worth your time or your efforts to help him feel comfortable and accepted. Open your eyes, then the door and run.