Who has had it and how did you go and repair the relationship?

I had a bit of a freak out and my partner needed space due to it. I've been anxiety spiraling for weeks and then had a really really bad day. I accidentally bumped into my partners other partner(new) and then ran into her again while I was out with my(our) partner and I said some things that I shouldn't have.

My partner was trying to deal with my anxieties. The blow up was just too much. I don't recognize the person that was.

I don't know how to repair. I'm afraid I fucked up. We talked about a couples therapist before the blow up.

I'm reading Polysecure. How do I fix this?