Sex after gall bladder surgery

Ok guys I need some advice. I had gall bladder surgery in November and since then I don't feel desire to have sex. I just can't get into it or think about it anymore. My partner is 100% supportive he tells me not to worry about it and he understands its not my fault but I can't help getting annoyed at myself and feeling like im useless. When I said this to him he of course reassured me not to worry about it he said things will work themselves out. Has anyone else went through the same thing if so how did you overcome it?