I’m a horrible best friend

What I’m about to say makes me sound like such a bad friend, but I have no one to talk to it about and I really need to get it off my chest so I’m just going to rant here.

My best friend of 6 years got a boyfriend about 4 months ago and I wish she never met him. I’m happy that she’s happy but he’s completely ruined everything. We haven’t seen each other in months because he lives with her and he won’t let her come over to my place, and I don’t want to go over to their place because I’ll just be sitting there either watching them argue or makeout. She’s changing, she’s doing things and saying things she’s never even think of before him. She’s not the girl I know and it’s breaking my heart because I love her like my sister. I don’t know what to do😔