Should I cheat on my husband? Complicated issue...?

I love my husband VERY much. We have been together for three years, married for one coming August, but we have only had sex a total of five times, two of those since we have been married. He has NEVER finished and says that he doesn't have sex with me because he's too tired because of his illness. He isn't ill anymore, he's pretty much 100 % better already and has been for months. I'm 24 and have been sexually deprived WAY too long, but I have never done anything about it because I love my husband. I have a friend coming into town next week, and we have shared intimate feelings about each other before, but never did anything. I am seriously considering sleeping with him, but am afraid of what it might do to my marriage, whether or not my husband finds out, I will know and I'm scared of feeling so guilty. Am I wrong to think about cheating on him or am I justified? I have been pleasuring myself so long that porno hardly has any effect on me any more and I feel so numb. It's useless and frustrating. Someone please offer some guidance. Thank you.