Hi @alertbattle,
Welcome to the Forums. My name is FloatingFeather an I am one of the peer support workers at SANE. You have found a safe place where you can share your story and your feelings in an anonymous space. I'm really glad you have reached out for support and understand it can be a bit confronting at first but I'm sure you will find there are many warm people on the forums with a lot of lived experience.
When I was reading your post I really felt for you. What you are going through cannot be easy and I would imagine you may feel vulnerable in this relationship. It's never a nice feeling when someone in a relationship stops it abruptly, particularly with no (limited) explanation. It would also be difficult with him being your work supervisor - does this mean you will still have to see him on a daily basis?
From what you write, he seems very dismissive and cold in relation to the way he has stopped communicating with you. I can understand why your anxiety has kicked in. The fact that he has done this before is a little concerning - it's never a nice feeling to be picked up and put down by another person. I would think you at least deserve to know why he has done this and be given the right of reply.
A very good friend of mine was married for 30 years and then her husband left her for another woman. I think one of the main things that caused her pain was the fact that he made a decision on their behalf and didn't consult her about it. So I can understand somewhat how you are feeling.
I really do hope you can get some answers to your questions from him. If you feel like your anxiety is getting too much I would encourage you to reach out to your GP, a trusted friend or family member for support. Somethings are too much to take on by yourself.
Warm wishes,
FloatingFeather
PS. On an aside, if you want to directly chat with someone on the Forums use the @ symbol and then start typing their name directly after it. A dropdown box should appear, and you then select their name. This ensures that they are notified of any posts you mention them in.