Will I ever stop feeling this way?

My boyfriend and I have been dating for just over 2 years. Just as we had started dating, his divorce had been finalised, he also has a 4 year old son from that relationship. It was a messy relationship, they were together for 10 years, he married her because of pressure and the marriage only lasted 8 months. He was the one who left and in the short time of being married she fell pregnant. As I said, messy.

So, my issue is, he already has a child and has been married. Just so you know, I'm 26 and he's just about to turn 35. Now I knew of his past when I met him due to having a mutual friend filling me in, but I obviously had no idea really what I was getting myself into.
From the very beginning he's been afraid to hurt her feelings, mainly because he still feels guilty for their past. So basically, he does what she wants 90% of the time. Slowly he's starting to stand up because there has been times when I've been hurt by him putting her, not the son, before me and I can't stand it.
Anyway the point is, I'm REALLY struggling to deal with the fact that he already has a child and has been married to someone. I literally can't talk about another child, or my future child with him, without him comparing it to his own. I'm terrified this will be the case when we have a baby, will it be as special or will nothing compare to his first born? I know it sounds stupid, but the way he talks at time genuinely upsets and scares me.
It doesn't help when I go to his mums house and she always talks about his ex and compares us, he's called me by his ex's name 4 times now, even in front of his mum. It took about a year of me nagging and getting upset for him to get his parents to take his wedding photos down, even after being separated for 3 years??? Is that weird?? I understand they were together a long time but seriously, move on?? When I met his friends they always talked about her and asked me how it went meeting her, like it was a big deal. It's like no one can move on from them? I feel like I can't enjoy a relationship with him without his past being a black cloud over us. I get extremely jealous when he talks about his child or when he goes away every second weekend to look after him, I don't know why and how to stop it.
I'm starting to resent him and his past, because I feel like I've missed out. But I love him and want a future with him. I feel like I'm in a constant battle with how I feel, some days I'm fine others I'm not. Any advice would be really helpful.