I'm sorry you're having such a tough time. I've gone through this with my daughter who is 17 now but realized when she was much younger that I often had SI although I tried to hide it from her. I made her a promise that I would never leave her in that way and whenever she is worried now we verify that promise. I also typed up a safety plan that I went over with my therapist and showed my daughter.
Sometimes she still worries and I hate that. You're not alone. If you need to talk I'm here.