I dont know what to do, please help.

I have been married to a wonderful husband for 11 years, Im 30 and he is 35, we have 3 kids. He makes me happy in every aspect but for some reason If have the "need" to be with another man, I cheated on him once and had the oportunity to do it a seond time. I dont know what to do, i love him and dont see my self without him. I cheated on all of my ex boyfriends. I think this is a problem. I am in therapy with a counsel and he thinks i have an addiction. Has this happened to anyone?