Ignores me when he’s with his kids

It might sound like a childish reason to be upset but my boyfriend ignores me for hours when he’s with his kids. He doesn’t reply my messages and forwards my calls.

Back story: after dating for a year we broke up and he got back with his bm, went even far as to move in with her for 4 months. We got back together months later but I am not over it. I don’t think I ever will be. Now every time he forwards my call I think he’s playing “happy family” with his the mother as well. I’ve spoken to him numerous times that forwarding calls bothers me, rises my trust issues, and makes me think intrusive thoughts. He says he’s going to change and it’s been month and he hasn’t. He does this every Thursday!!!

He doesn’t tell me he’s with his kids, but I suspect it. I’m happy he’s an active father but there should be no reason why he cannot answer the phone for a few seconds.

Am I wrong for thinking’s he’s playing happy family with the bm??