so i found out my bf doesnt like his mom right now. and the reason why is because last friday she…

so i found out my bf doesnt like his mom right now. and the reason why is because last friday she told us to spend the entire weekend over there so we did. but on friday we get there and we go to sleep and wake up at about 11 pm just to see her getting ready to leave to go sleep at her bfs house (the abusive one). he didnt say any thing to her till the next day. he tells her that how dare she choose him over spending the night with her only grandson and that we werent gonna let her see him anymore. she didnt react to it as if he was being serious, all she said was "oh michael, calm down quit joking around" now im thinking about taking my son to universal studios on sunday and inviting my sister in law since shes in town... should i tell her not to tell her mom or is that messed up? cause honestly right now i dont want her aroud him.