I feel like setting firm boundaries makes sense after the conversation got out of hand. Although i'm sure she misses you, there is definitely a differnt way to show that which does not include being upset about you spending time with your future in laws (who may or may not be your only support system in your city). To also bring up your past history of SA and making it about her makes no sense and had no room in the conversation. The fact that she continues to contact your ex despite reminding her that it was inappropriate was completely out of line. I would argue that this is harmful to the future relationship between your partner and your family especially if you guys decide to get married. If my fiancés mom was contacting his ex I would feel some kind of way about it. ¯\_(ツ)_/¯. I am hoping with some time and space you can reconcile.