Crazy Ex???

I’m a little anxious typing this but here I go.. I’ve known my s/o for two years now. We’ve had a really good relationship. Yeah several arguments here and there but who doesn’t have them. He had warned me about a past toxic relationship he had been in and about his “crazy ex” I didn’t think much about it and let it slide. Now we recently got engaged and we are both super excited to move on with our life’s as one. Everything seemed to be going good until about a month ago. His ex popped into his Facebook messages and I couldn’t have it. Turns out while in a relationship with her, she had gotten pregnant but she decided not to have the baby. Her excuse to talk to my s/o is “she gave him a picture of an ultrasound and now she wants it back” 🙄 my fiancé does not have the ultrasound picture and we both knew this was going to cause his ex to basically go crazy. He’s been polite to her even when he told her about him not having the picture and her not having a good response to it. As of now we both deactivated our Facebook accounts so she has no way of contacting us. But I’m just scared that she will eventually find a way and try to pull a quick one and try to get in between us. I’ve talked to my fiancé and let him know how I feel about this situation. I don’t understand why shes asking for the picture now that’s she knows he’s engaged.... What worries me is what she could do now... What do you guys think? Am I over thinking this situation??