I Made A Bad Decision

I’ve had a crush on one of my friends dad ever since the first time I saw him. He’s in his 40’s and very good looking with his wife and three kids.
A few weeks ago I stopped by their house to see if she was home but the only person home was her dad.
We talked for a few minutes then I thought he was flirting with me so I kinda flirted back but didn’t want to make it too obvious afraid I was wrong.
Then he started asking things like if I had a boyfriend, what I like to do, then shocked me asking if I sexually active like his daughter.
When I told him no that I was a virgin he hesitated then asked if there was any way he could be my first.
I was shocked but at the same time flattered so just meaning I appreciated the compliment I said that would be nice. He immediately grabbed my hand pulling me down the hall into the bedroom.
All along I was telling him I didn’t think we should do anything but he kissed me and I melted.
The next thing I knew we were on the bed kissing passionately then he started unbuttoning my jeans and I said ohhh Mr. S_____ but he stood up took my shoes off then pulled my jeans off.
He took his pants off getting back in the bed ran his hand in my panties fingering me and I completely lost it.
After he had me a complete mess he got himself out pulled my panties to the side then had sex with me. When he came in me my whole body shook. Afterwards we both agreed it had been enjoyable then I cleaned up and left.
I was a fool not taking plan b and he got me pregnant my very first time. I haven’t let him know yet but plan to soon so we can decide what to do.