I think we have been caught?

I separated from my husband 3 months ago and have been dating my male mate secretly for the last month or so. He isn't the reason for our divorce, we have just started to spend more time together and one thing has led to another. The problem is that a mate of mine's Mum was out the other night and was positive she saw me and this new boyfriend out on the town holding hands in a bar. I have denied it to my friend and although she appologised to me, I am petrified that she knows that I have been seeing this guy because at first she text me to say I had been framed, how long have I been seeing him for? I was petrified because it must have looked really bad especially as I am still living with my husband at the mo until his house is ready to move into. My husband goes out 3-4 nights a week all night but no one sees this as disrespectful. I haven't seen my friend's Mum many times so she might think I have a double. What if my friend tells my husband and our other friends?