So my boyfriend has a friend let's call her C he hasn't seen her in almost five years and just met up with her again this week the next day she texts him and her fiance saying that she still has feelings for my boyfriend. Sometime in July he's supposed to go with her and her mom to this event in LA (Birthday Surprise) I didn't like her from the beginning but disregarded it because he told me not to worry about her she's getting married. so I told him I already don't like her because of the fact that he told me I have nothing to worry about at all because she is going to be married and the next day she tells him she still has feelings for him. I told him the only way that I will be okay(still don't like her but won't cause drama with her) with her is if she writes me a message saying that she respects our relationship and she will not try anything and if she does try anything it will fall back on my boyfriend and he will no longer be with me does this sound reasonable to you?

I know I don't like her at all, but for him I'd compromise. I trust him but I do not trust her at all. I want her word, saying that she knows if she tries anything that she will hurt her "Best friend " and be the reason if he decides to stop talking to her after.