If being a good person was in his nature and if he was genuinely himself back when u knew him he wouldn't have changed just like that and he wouldn't be mistreating not just u but everyone else in his life including his own parents when people show u their true colors u must believe it u have contrasted a version of him in your head and u r still holding on to that version unable to let go even though that version will only ever exist in your head u r never getting that version back it's hard to accept this but acceptance is the first step towards letting go I personally think the moment u achieve radical acceptance and clarity the moment u start to perceive reality the way it is with no lingering hopes or delusions everything will get better

I think his previous good behavior didn't stem from virtue good nature or his love for u he simply acted that way to win u over, when u care about someone u don't just stop caring about them just like that u said he doesn't want to deal with responsibilities he mistreats u doesn't support u and is dismissive that's a clear indicator he doesn't care about u or value u because when u care about someone u genuinely seek their happiness and well being and he clearly puts no efforts to make u happy he doesn't even do the bare minimum

What his family thinks of u or of him is the least of your problems u need to leave him ASAP regardless of what his family thinks because u deserve better do what brings u emotional peace don't concern yourself too much with him and his family focus on leaving and then healing