Help please

So I am currently talking to someone who has a criminal past.. but every since we’ve started going out he’s completely changed. His mom even told me. But my sister isn’t to fond of him because of his past and I’ve tried to explain to her that everyone has a past but she just talks bad about him and it really breaks my heart because I hate to admitted, but I’m falling for him. I was in a really abusive relationship and it messed with me mentally and everything else above. He is always there but sometimes I just get a weird feeling, but he has a real job unlike my last relationship and I just don’t know if it’s that or his past. I really do care about it... I just need someone to talk to me I guess....