Reconstruct myself or learn acceptance

While I know my current situation is based on medical horror, I still feel responsible to fix it. I should be able to fix anything in my life, family, relationship. Even if it's not possible, I feel as though I am a complete failure as a husband, father, person.
The first step is to diagnosis the problem(s). This is always difficult and/or impossible to do. There are so many factors. There is cold hard facts, personal feelings, devils on shoulders and so on. So hopefully putting them all down in front of me can help me see the big picture.
     So we start with the facts. I've been married 12 years.I've been cheated on twice, once about 4 years ago and once about a year ago.
   My wife has had a hysterectomy less than a year ago. She struggles with her weight since then. she is depressed. She has no sex drive.
   So facts seem simple, feelings do not. Feelings say something is wrong with me. I'm un desirable, I'm unattractive, not sexy, not something. 5 years ago she would flirt. She would jump on me, straddle me on the couch, make out anywhere, jump in the shower with me, pull the car over for some fun. She has refered to all that as a fairy tale that only happens in movies and on tv. Even though we had it the first half of our marriage. I can almost accept that maybe its age. Old people dont make out, or have hot wild sex. Although when we decided for a brief moment to get a divorce, we had the hottest sex we had in a long long time. So is being commited what kills it? She has had her movie only fairy tale twice. With 2 separate guys at clubs. Hot dancing leads to hot sex in cars or hotel rooms. I ve tried to duplicate. I feel so akward dancing, but with my wife it is hot and an extreme turn on. But with me I feel as though I'm not the hot turn on that other guys are. No hot making out or sex follows. Car sex or bathroom sex would be inappropriate or gross. so it must be me? While I desire sex, I more desire being wanted.when we do make love, I feel like she is forcing herself to. Its laying in bed for 30 minutes then maybe reaching over to touch me and get things started. Which is awesome, sex is great, my wife is gorgeous and turns me on just by looking at her. But its never making out headed into the bedroom and undress eachother because she needs me then and now.its never we can't wait to get home. So am I the problem? Is it really a fairy tale.if so why did we have the fairy tale for so long. Why has she had the fairy tale recently without me. Obviously the hysterectomy plays into it. But we lost the fairy tale before that. I feel so selfish, wanting for me, when she is struggling so much. I know medically and emotionally she is broken. I want to fix it so bad, because I can't stand to see her hurting. And unfortunately I am emotionally broken too. So the question is reconstruct myself or accept. Reconstruct and lose weight, become a better dancer, get some muscles, and hopefully become desireable and so hot she can't help but to rip my clothes off. Or accept. Accept that nothing I can do can make her want me, we have out grown spontaneity, that medical reasons are the root of the problem, and that fairy tales no longer come true.
   un fortunately I always think I can fix things, therefore if I can't, I must be doing something wrong. Which of course makes me think I'm the problem. Therefore all I can do is cry and think of solutions. And I can't find the damn instruction manual.