Did I make a mistake in breaking up with my (mostly wonderful and gorgeous) GF of 7 months rather than agree to an open relationship?

TLDR: my Gf (who I dated for 7 months) was weirdly obsessed with pushing me to hang out with my ex-wife and her new husband. She later asked me to open the relationship and allow her to hang out with her ex BF. I declined and broke up instead, but am wondering if that’s a mistake.

Full Post:

So I [early-40s M] was head over heels over my GF [27F] until she kept pressuring me to hang out with my ex and got super mad at me for refusing. As detailed in my earlier post, she got super mad at me and gave me the cold shoulder for 48 hours over it.

When she finally spoke to me again we talked it out and she confessed that she wants an open relationship. She wants to keep seeing her ex-boyfriend (who I’ve met once before and was initially introduced to me as her queer ex-roomate).

I was upset with her lack of candor about her ex-BF and decided to just break things off. I am also weary of open relationships since it seems that women tend to have a way easier time finding guys to have no-strings sex with.

We’ve been broken up for a few weeks now, but have continued to hook-up and going on (rather expensive) hang out sessions which essentially feel like dates. My ex-GF is stunningly beautiful imo and used to work as high-end escort, so the sex with her is so good that I truly don’t feel like I have the willpower to resist her.

Ex-GF keeps asking me to re-consider being an open relationship with her. She says we’re basically acting like we’re in one, which is kind of true.

Am I making a mistake in refusing to be in an open relationship? Or should I continue to hold firm (or even try to cut off contact with her)?

I’m leaning towards cutting contact, but before our breakup I already booked a trip for us to Amanyera for Valentines week (she’s dreamed to visiting an Aman resort for years) and as a man I don’t have the heart to pull the plug on that. I know it would really hurt her. Thought about just gifting the resort stay to her and cutting contract, but then I would feel bad knowing she’ll be staying there with someone else.