How to deal with boyfriend staying at his baby mama's house for Christmas?

Me and my boyfriend have been together almost a year and with Christmas nearing I am feeling very uneasy that my boyfriend plans to stay at his ex's house for Christmas. I feel this way for several reasons mostly because his ex still wants him and is constantly trying to interfere with our relationship and that I have yet to meet his daughter because he does is afraid if he request this that she will not allow him to see his daughter. Aside from the situation with his ex we have a healthy normal relationship and live together, with my 3 children from a past relationship.
How to deal with boyfriend staying at his baby mama's house for Christmas?
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