Advice for women dating men with children please

Domynique • Happily taken and a mommy to a beautiful girl

My SO and I have been together for 10 months. He has a 18 month old with previous girlfriend of 2 years. They have been broken up since the baby was born and always had a bad relationship afterwards. She previously would call him almost every night and beg to get back together and in november stopped allowing my SO to see the baby until about a week ago. Now she calls at night to "let him talk to the baby" and invites him to appointments. He tells me he doesn't want to be with her but hearing them laugh on the phone and talk makes me feel other wise. I would never get in the way with him being with his family and now I just don't know what to do.

Do you ladies have any advice?