Jealousy/dislike ruining my marriage!?

I've been told that I need to find a therapist besides the church. I am losing my medical insurance next month, or in a few weeks and can't really afford to start counseling. I'm extremely jealous/have much contempt for my in laws. It started right away, when I found out that my MIL might be richer and hotter than I am. I'm petite and young, but for some reason I have it in my mind that I am lesser than them and they are so much better than I am which causes me to have a "complex" and feel I am a loser. They insist that I am imagining all of this and that its ridiculous, but I have it in my mind that I will never be as good as those people and I will not back down from my stance. My self esteem is so low, and my husband and I fight all the time because of how much I dislike his parents! I've told them off again, and now they want nothing to do with our marriage/giving us advice which is good actually. I told them "Ive never been your biggest fan let me tell you, I think you're narcissistic and conceited. Both of you are". What is wrong with me? I've seen a psychiatrist and she diagnosed me as major depressive. What else can I do do shake these feelings?