I like my friends crush! He likes me too. Help

So, we all work together. Someone new started me and my friend instantly both was physically attracted to him. We joked about who would get him first, flirting and generally winding him up. He took it as much as he gave it with us.
I then got promoted which meant I wouldn't be in as much regular contact with the guy. However he made an effort to stay in touch with me.
He asked me on a night out but I couldn't make it. He then went out anyway and bumped into my friend whilst she was out.
They went back to hers after the night out. They where very drunk and ended up sleeping together. She has now developed a deep crush on him. Naturally as a friend I back off and no longer like him because that's the friend code right?
Since then he has backed away from my friend and stopped the flirting and joking... However he made more contact with me. He asked me for some dinner so I said of course let's invite my friend. He seemed off with that and I asked her she said no which then made him happy. So on the weekend we went out for lunch it was lovely, getting to know him on his own. No jokes needed. That was that... I didn't think anything would happen again. Then I needed picking up from somewhere so i asked him and he came well out of his way to pick me up and take me home. In the car there was definitely an atmosphere. It made me feel nervous but in an exciting way!
We then have been messaging on the night A LOT. My friend knows all of this I just tell her we have been talking nothing interesting. But for me it is interesting, we are really getting to know each other. Then out of the blue he asked to take me out on the weekend for some drinks he will pay! I said yes I told my friend and she told me to go it will be nice for me to get paid out however if I touch him she will kill me. - sexually touching. I wont baring in mind.
Then he came to my part of the factory to bring me a plant i had been saying I wanted for my office. He went out and bought me one. I thought it was really cute.
He then is messaging me on the night. Bits of flirting going on but nothing serious because I can't keep my friend out of my head.

Am I out of order for liking him? I know he likes me... What if things go further and we want more how do I do that to my friend or don't I go there at all? I have really really made a connection with him. I do tell my friend everything we have planned and tell her I wont go if she doesn't want me too. She said it has nothing to do with her she just fancies him. I'm just so stuck right now.