Broke up with my partner of 4 years

I broke up with my partner of 4 years last night. It’s been something I’ve been thinking about for a while, we’re very different people than we were when we first met and I’ve just fallen out of love with her in a romantic sense. I still love and care about her so much and I hope we can stay friends. As much as I know it’s for the best, I feel absolutely broken by it.

My other partner is also dating her, but I know he plans to end the relationship with her too when they can chat in person. I’m finding it so hard to navigate - I never even considered polyamory until I started dating my now ex, and I met my boyfriend because of her. I feel horrible breaking up with my girlfriend and staying with the boyfriend that I only have because of her. It all just feels so complicated and overwhelming and my brain fully just doesn’t know what to do with this all.

I’m not finding usual breakup advice particularly helpful because it’s not like I’m now single, I still have my boyfriend, I’m just not with my girlfriend. And the breakup has been very amicable and I want to stay in touch with her, and she wants that too, it’s just so raw and difficult right now.

I don’t really know where I’m going with this. I just needed to vent to people who are more likely to understand this whole mess. And if anyone has any advice on dealing with all of this I welcome it.

Thanks for listening.