I'm Having An Affair With My Sister's Husband

I moved in with my sister and her husband around a year ago due to financial problems and to help her out, the problem is that within a month my brother in law started hitting on me very strongly.

At first I was in shock because the guy hated me from day one but I was extremely depress due to my situation and felt lonely one thing led to another and we started having s*x, I feel used and guilty as hell we never talk about it he doesn't say anything he just does his thing and forgets about me until he is in the mood again.

I know this is wrong I am betraying my own blood but I just can't stop its like an addiction, he is using both of us for his own fun and pleasure I am so desperate I can't move out because I will have to have a very good excuse, if my family finds out I will be in so much trouble I come from a culture where its always the woman's fault, men are considered men and women tramps.

Sometimes I feel like I love him but then I think about the whole deal and realize how stupid I am this relationship has no future it was doom from day one. I feel jealous and angry sometimes but mostly confused I am fairly attractive I know I can get a man that is single and available but I am scared. I feel like I am losing my mind I cry everyday because I don't know what to do.

Please help I need advice