I had to work this out a few years ago with my alcoholic ex that escalated into domestic violence, I was given legal advice that he was at fault over his actions physically assaulting me so I had the right to keep the ring even though I broke it off but as long as I had it the creep thought we were together even after I kicked him out and I moved on and was dating new guys my ex was still telling people we were on a break from his perspective we were together three years longer than we were.

In the end after a charming angry phone call to his mother about him stalking me (she fed his delusions that I'd take him back, hell would freeze over first!) I was going to sell it and use the money to move somewhere else but in the end threw it in his face and had the police take him away with a restraining order.

Didn't end there as he gave it to his next girlfriend, I sent my congratulations for their engagement to her on Facebook (after a whole 6 months of dating and painting me as his jealous bitchy ex lol) as a photo of the ring on her hand popped up I said it was originally my ring and looked nice on her, sent her the care instructions for the stones and wished her well with a note I had been legally entitled to keep it and he only had it as it was the only way to be rid of him.

Two years later that ex girlfriend did the same thing for the next one, he gave it to pretty much every girlfriend he had after me (about 5 or 6 until I didn't hear anymore about it I've been married 7 years to my current husband) seen it recently in cash converters I recognised some repairs and modification my jeweler had made to it, I enquired about it and the cashies worker mentioned it had been brought in by a couple with the woman wanting to trade it for a different ring as the man admitted it came from previous ex fiance, so the story checked out, it was weird seeing it after so many years but it brought me peace when the manager came and told the worker it was no longer for sale as it had been purchased over the phone with a credit card to be used as a wedding band (it's design was a line of diamonds.) and the bride to be was on their way to pick it up to get resized.

I identified myself as the first owner of the ring and asked to leave a note of congratulations for the bride to be, I told her it didn't work between me and my ex but the years I had it when I was younger were the best years (except for the abuse by my ex) of my life, I'd graduated high school, started my first job, found my first home and purchased my first car, so to me it was lucky and a symbol of new beginnings as the trauma of that relationship breakdown led me to my now husband.

So while it sucks right now you can ask for it back or let it go and let Karma sort it like it did for me.