my boyfriend situation

I am 23 years old and my boyfriend is 34. he has been divorced around 4 years ago. we have been together 2 years. we loved so much for his side I know he love me because he gives me time, he takes care of me always. he likes to resolve me problems. etc. the problem is that every weekend, he goes to take care his children in his ex wife's house for one day. I tried to accept this situation but I can't. I think his ex wife still feel something for him. I asked him if he thinks to come back with his ex wife will be good for the children and he told me that he won't do that ever. I love him so much. he wants to have 2 children with me. sometimes we argue about his situation I don't want him has any contact with his ex wife. I don't know what to do his situation makes me think that if I get married with him I won't have a nice live because of his other children and the other woma. :(