I sound like a broken record on this site but here I go again. Your wife knows 100% that you're a guarantee for her. She can do whatever she wants and you'll still be her safety net to fall back on if she fails to find a suitable replacement for you.
She'll never respect you if you stay in this position. Don't be anyone's plan B, ever. You're better than that. Work on the things you need to work on about yourself. Make yourself a better, more attractive person, but detach, do some new GAL things, and start moving on. If she does truly love you it'll snap her right out of this crappy behavior. Honestly she's just a cliche at this point and everything she's doing is textbook so the textbook 180 response should work but you have to commit to it.
