Baby Mama Drama

So my boyfriend and I been together for 7 months now. His last relationship was with his kids mother they have twin boys together  that are almost one. Well now that we have been together she now keeps the kids way from him and the only way he can see them is if he go and sit at her house with them he can't bring them around. And she always message saying she miss him and want to work on things. Am I wrong for feeling upset and insecure??