Is this going to make my boyfriend jealous?

My boyfriend told me he had a crush on his friend Nicola. In the past, i've kept my ex-boyfriends as friends, just hanging out. No flirting, no anything. We have the same friends, blah blah. But, every since my bf started talking to Nicola he's been different. I read a facebook message from him to her. He said Dear Nicola , i love your hair, i love your smile and i love your ***. But then he said jk after the *** part. I've dropped all my ex-boyfriends as friends so my current wouldnt be mad or jealous. & know he's flirting. What to do? Should I make him jealous and mad by flirting with my ex-boyfriend?