Is it normal to have lustful thoughts about my stepdaughter?

Ok, I know it's not normal but I've had sexual feelings for my 26 stepdaughter for about 4 years now. We lived in different countries for a while and were texting each other on a regular basis, nothing bad in the beginning, just usual stuff.
Then, one day we somehow got onto the topic of sex and I found myself getting aroused by our messaging. I then started to have desires and fantasies about her. I knew that this was wrong and I do love my wife, but, it was like I couldn't stop. These texts went on for a few years, almost flirtatious but slowly they got more and more explicit until one night after a work function I text her "I want to fuck you".
Everything changed. I had stepped over that line.
I felt terrible and guilty and tried to explain to her that I was drunk (no excuse I know) and that I didn't mean it, but sadly, deep down, I had meant it.
The texting stopped but the damage was done. She stopped trusting me and went through he'll with feelings of guilt. A few weeks back after going to counselling she told her mother and the shit hit the fan. As it should've!
We are talking, my wife and I but for now my stepdaughter can't speak to me.
Don't get me wrong, I know what I did was sick and a gross breach of trust as a parent and husband. I am in counseling myself now and basically questioning who I thought I was, what the he'll I was thinking and basically questioning everything about myself.
Over this period I NEVER once touched her, the thought of physical contact never was on my radar, it was text only, not that that is less wrong.
Has anyone else been in this situation and how the hell did you get through it?