I Lost A Family Heirloom That Was Given To Me By My Ex As A Gift. Do I Have To Repay Him?

My ex (61 M) broke up with me (F 46) last November and demanded on the spot that I return a necklace that he had given me while he was screaming at me in my doorway. The piece was a necklace comprised of a single amethyst on a gold setting and gold chain that belonged to his mother, who is still alive. Quite honestly I had every intention to give it back, but I have torn my house apart trying to find it over the last few months, and I still cannot find it. At this point, it is safe to say it’s lost.

He is now threatening to sue me for $7500 for the necklace, which is a value he set for “emotional distress”. He does not have any appraisal for the necklace, much less a photo of it. Initially I was trying to be kind and offered to replace the piece with a like piece, but he has been so rude that I’d just as soon not deal with him anymore.

Do I actually owe him anything from a legal standpoint? I really just want to be free of him as he’s been bullying me and has shown up at my house and work to try to talk to me. I am located in CA.