I don't know what to do. Just need to vent and any advice is welcome. 

I fucked up. A bit. 
I started a new job at a call centre, and I was sooo happy! So much so that it quickly changed to a reaaaaally high mood. Not manic, but as high as it's ever been. And then this guy at another location started messaging me. And he was soooo nice. Then flirty. And I didn't realize how flirty I was being, or how out of character it was for me. Before I knew it, i was telling him we should be together and I wanted to run away with him. I was texting him, and snap chatting... with my husband of 15 years whom I love in the same room. 
This is weird for me. I'm an avoidant type. I know how I am with guys that are nice to me, so I try to stay away from them. But because I was so euphoric, I went right for it - from hey, you sound cute to let's hook up in less than 2 weeks!!

On Christmas Eve, it all came to a halt as I finally saw how I'd been acting. I am now in the deepest depression I've been in for a while, self harming and all. I wish I could just ignore the guy, but I work with him. And I still feel that tingle when he talks to me. I've led him on, and he keeps trying to get me to say I miss him or I want him... but I can't, even though I do want him. Bad. 
I know it's lust, but I can't get him out of my head. And I can't hurt my husband. But I keep crashing and sending him heart emojis and telling him I need a hug because I feel so sad. 
And then in a month or so they may send me to his centre to meet the team, and I'm so afraid I'll do something terrible. 

Anyway that's it. My therapist is out for the holidays, and I don't want to get into this with the crisis line. I haven't done anything like this in the 15 years I've been with my hubby, and I'm so lost and confused. Thanks for reading