what would you do?

my significant other recently became friends with a girl. they used to be very close, but had a big fight when we started dating and cut each other off. our entire relationship, she hasnt been around. so i cant lie, i felt threatened when she was back. i have serious trust issues, ive been cheated on in every big relationship ive had. he knows. he stays the night with her. he use to sleep in the same bed as her before they stopped being friends. (while we were dating.) i begged him not to this time. he talks to her all the time. it makes me feel like im in second place. he made plans to get a house with her. he didnt even tell me. "it wasnt solid and i thought you trusted me anyways." i just thought i was important enough to be told his plans. and thought about before he made them. especially when they involve living with another girl.. and its not just about trust.. its about respecting my boundaries. we got in a pretty big fight last night. and once again, in the end, i ended up apologizing and telling him i'd change. i'm so scared. but i'll be the one to change, i guess. would you feel comfortable with your boyfriend having such a close relationship with another girl? i feel like im losing my mind.. i feel guilty for feeling this way.. im trying to understand and be more comfortable but god he makes it hard.. i told him this is the kind of stuff that ends relationships but he just doesnt care. i dont mind that he has a close girl friend. its just the sleepovers.. and the constant talking.. the attention she gets from him.. the talks about moving in together.. it doesnt feel right. i don't know what to do.

and on top of it all, i think im pregnant