I sorta resent my best friend...

This is a little vent-y, but I desperately need advice.

P has been my best and one of my only friends since high school. We lived pretty far apart but we message a lot and stayed in contact. Once we graduated, we were able to hang out in person more and get to know each other better. At first it was fun, even if i was sort of nervous.

Now I don't know if I like her.

Shes loud (I have sensitivity to loud noises), sometimes impossible to talk to (like she'll sing a literally 9 minute long song without letting me get a word in edgewise), refuses to discuss serious matters even if I really need to talk, doesn't seem to respect my discomforts, has started disrespecting my fiancée S and saying things about S that REALLY bother me, and has said some things that make me just generally dislike her as a person.

But I can't leave her. One, she's my only friend, and two, she's going through some major crap right now and I'm like the only one who can help her through it. I'd feel awful if I just abandoned her, but honestly every time we need to meet up I feel like I'm using all of my spoons just to emotionally deal with her. I don't think my fiancée likes her either. They ""playfully"" bicker back and forth but I think they might hate each other. P is also reaaally jealous of any sort of romantic relationship, so we can't all hang out without P getting super depressed.

I don't know what to do...