What to do?

I have been married for a little over 2 years, our sex life itself isn't completely lost but I think it may be getting that way. during the delivery of our daughter she tore the cartilage that connects her pelvis in the front. so sex was painful in certain positions and most of the time she didn't want to have sex.I ask if she minded that I masturbate to repress if you will my "needs" and she said she was ok with it and sometimes would "help" me. This was 18 months ago and she is a lot better as far as the pain goes we probably have sex about 2-3 times a month. My what to do questions is this, I just recently returned from a trip, I was gone for 4 days, I told my wife I was coming home early cause honestly I missed her and our daughter and I didn't need to stay another day.After I got home and we put our daughter to bed i wanted to get a bit frisky and my wife told me she was tired and it had been a hard weekend being alone with Sophia (our daughter) and so we went to bed and I snuggled her for a bit to relax and just be with her. about 2:45 am I woke up to the sound of my wife using a vibrator on her self right next to me as I was asleep.I know my wife masturbates I don't mind at all. I work a shift schedule and am gone from afternoon to early morning. What upsets me is that she refused sex with me and chose to masturbate instead.I am very self conscience about my sexual prowess as it isn't the greatest but I am working on it. I just don't know exactly to handle this.Any advice would be helpful