Hit On

I went out with an old friend whose name I wont mention. But this guy used to have a thing for me, like really hard. But we hadn't talked in years, so when he messaged me to say hi, I figured he was just talking, bored maybe, whatever shooting the shit. It happens. But he asked me to hang with him, so I accepted, having nothing better to do.
But what does the guy do? He starts getting handsy. He knows I have a boyfriend, we talked about Mark for chrissake!
So I made sure to text Mark telling him who i was with and where in case anything happened where the guy tried to kiss me or something, so that if that happened, it wouldn't come out of nowhere at Mark and upset him.
When I got back from whatever you want to call it, I told Mark what happened, and let's just say he didnt take too kindly to it. He said that I shouldn't have gone out with the guy if I knew he had a thing for me and made it sound like I had just cheated on him, which I hadn't!
I wish Mark wouldn't say things like that. I'll probably have to go and explain the whole situation to him because it's not my fault. I didn't intend for this guy to behave the way he did. I mean, geez! I barely expected it, especially after having no contact whatsoever with him for the last year or so. I figured if anything there would be light flirting from his end and that would be it. I mean, jesus! we talked about Mark! He asked if I was happy with him and why I liked him, how long we'd been together, how we met, all of this nice stuff. I really didn't expect for him to do the things he did. And it made me really uncomfortable. I mean, first of all- it's him, I have no feelings towards him whatsoever, he's not even attractive; Second HIS hands didn't belong on me; Third, he asked if I was happy with Mark! Of course I said yes and he still tried! That's retarded! Plus, you know what? I don't even know anymore I'm so frustrated and exasperated.