Confused girl

I'm 19 years old and I've got the perfect job! Since our works Christmas do I have also become good friends with the owner/Managing Director. Me and the director of the company who is 41 and married with a 19 year old son, have always had flirty banter but the last few days it's been overly flirtatious where we have both been so over the top. He's been massaging my back and pulling at my knickers (as they were showing from underneath my trousers when I was sitting down.) I am really starting to want more but I don't know what to do obviously he's married and I shouldn't think anything but I'm not the one who is married I need some advice please no hatred I wasn't the one who started all this.
I'm single and he's really tempting me but is waiting for me to make the move so he can trust me. I want to but scared in case I get in too deep. He keeps starring at me with so much in he's eyes at the end of the day I know I won't be the first women to be in this position.