The In-laws

Me and my partner have been together for 10 years now we have a little boy and baby due in August, you'd think by now things with the in-laws would be nice??? I've reached breaking point now which is why I'm posting this for any advise. 
His parents/siblings have never liked me never made me feel welcomed into their family his mother always goes about Claire is college girlfriend that she wanted him to end up with and she wonders the kind of kids they'd have together all this is going on with me sat there having to listen so frustrating. I'm not pretty enough, I don't like all the same things they like, when I'm around them it feels like play ground bullying. His parents have a grand daughter from their daughter she is treated like a princess, her pictures is all over their house in every single room my son has only got one small picture in the living room, when it comes to presents my son gets a pj set, while their other grand child gets hundreds of £'s spent on her. I could go on forever.... I just can't take it anymore my partner doesn't like it but tolerates it he has already told them it's unacceptable and as my son is getting more aware and understanding of what's going on I feel I need to cut ties with his family??? I've put up with it for so long because I love my partner and I know family is important to him. But I've reached boiling point and I'm ready to put them behind me.