Is he seeing his ex again?

My boyfriend and I went through a messy seperation, when I discovered that he cheated on me. Since, we have been going to AA (for his alcoholism) and counseling for couples, to try and fix us. Well, while we were broken up he was living with the women he cheated on me with and her two kids. Although he has not been living with her and her kids for about 3 months now, my daughter has just started singing a song that she sang before when they were all together. To save identification of the people involved, I will just call these people Alice (her daughter) and Angela (the cheating homewrecking hoebag). My daughter has started to say Aaalice, Aaangela. Clear as day. She hasn't said those names in over 2 months and now all the sudden she is! It is wiggin me out. My boyfriend and I don't live together right now, and are just trying to get it together seperatly and take our time before rushing back under the same roof again, but I am freeked out! I don't know if she is just singing that again, because she knows it gets my attention, or if she even remembers those people or if she is just kinda remembering playing with the youngest daughter (Alice) and wonders where she is now. Angela has a facebook account, and it says that she is back with her ex husband and living on the other side of the state again. I asked my boyfriend about why she is singing that, and he tells me that maybe there is a toy or clothing or something that is reminding her of that skank and her kids, and he wants to have a garage sale or go to a mom to mom sale to get rid of EVERYTHING that she ever bought for our daughter that might remind her. Bottom line.... I feel like I am wigging out and losing my mind! I think it is time to exercise the right he has already given me to start checking his text messages and voicemails and such again. Maybe even get his pword to see his facebook profile. Something for a reurance.