I don't know what to do!

Sorry this is very long!

So I am 17 and I've been dating this guy who is about 6 years older then me for about 3 months and we were friends 4 years prior and it's been amazing! He's never pressured me into anything and he's been really understanding. But here's where the problem is: he was staying at my house for a few months over the winter and while he was at my house he started out being very helpful to us and kind to my younger siblings but after a while I think he became interested in me and stopped being nice to them and started being selfish and only nice to me and taking me out and stuff which was nice for me but I did not realize how mean he was being to my siblings and how much it hurt their feelings and I don't know if he does and this has become a real issue because I failed to see when the line was crossed and my mom never said anything because she felt sick and was stressed and she feels like he bullied them and they will be permanently damaged because of it. She says I always stand up for him and I'm blind and I'm sure that's possible because I really care for this person, but my mom says she never wants to see him again and he's never invited over again and she will never trust him again and she feels deeply deceived and I am at a cross roads here and I'm not sure what to do. I love my family so so much but I think I'm in love with this guy and I desperately want my family and him to get along even if we are just friends in the future but my mom won't talk to him about it and won't allow me to say anything because it "won't change anything and nothing he does will make me forgive him, people can't change this is how he really is" and I am aware his behavior was out of line but this is how he and his siblings behave around each other and no one said anything to him and he said to me he was trying to get my siblings to be more helpful. In my family we are super nice to each other all the time so no one has any experience with unkindness. I feel like he should have known when to back off and he didn't and I am deeply hurt by hearing what my mom and siblings said about him and hurt by what has happened between them. I love this guy and my family but I don't want to have to choose between them.