I Stopped But I’m So Ashamed And Embarrassed

I’m an assistant to the owner of a small firm. I’m 23 and have been married for a little over a year.
Since starting my job about a year ago my boss and I have become good friends as well as associates.
A couple of months ago we had an evening dinner meeting with some clients. At dinner we had a couple of bottles of wine. I don’t drink much so I got very relaxed and a little tipsy.
After the dinner my boss and I walked back to our cars which were parked in the parking garage at our office. He is a very handsome man in his early 40’s, married with two children.
When we got to my car he surprised me turning me around kissing me. I was just relaxed enough to let my feelings towards him show by kissing him back.
The next thing I knew we’re in the backseat of my car making out. I let him go as far as foreplay with his fingers getting me extremely horny. However when we were ready to go the next step I chicken out which was a good thing because I later realized I had been very fertile.
Things have not changed at work but I feel very embarrassed around him knowing I let him go that far.
I’m also ashamed that I basically cheated on my husband and could have easily gotten pregnant had I not chickened out at the last minute.