I can understand the insecurity and the jealousy. I could also understand grief and anger.

The puzzle here is the self-hatred. Are you feeling guilty about something?

I'm glad you are seeing a therapist. That should help. There are several ways to articulate this. You could start with a bare and dispassionate statement of the events. Or you could start with naming the emotions, as you have here. Your therapist should help you from there.