Spinning! Need help!

Just been chatting to a friend from work, who is also one of XN's best friends. He has no idea about XN and me.

We had to talk about a work matter, so this was definitely not a case of me fishing for info. I wasn't even thinking about XN.

Then friend starts talking about a big surprise party he attended last night. It was for XN's birthday, organised by OW. Fancy hotel, where the two of them then stayed the night. He also, without me asking, talked all about their relationship, how good they are for each other, how lovely OW is, and on and on.

Now I am alone. I am crying, can barely breathe, out of my head with insane jealousy. Feel like I am in the same state of crazy as when I first found out about them.

I need help with this. Please. How can he still have this effect on me? Where did my strength go?