Your Boyfriend/Husband's Baby Mama

My boyfriend lives with me and we are expecting our first baby together. He has two from two different women and I have two from someone else. Now he is technically married but seperated. His son's mother (wife) drops off and picks up his son at my apartment. Mind you, my boyfriend's name isn't on the lease. I don't like it because they were married 16 years and I have trust issues. We've never met but I think once she finds out I'm pregnant she will cause problems. How would you deal with the baby mama? And how would you handle this situation?