I'm Sandi2 and glad you found us to talk to. How much a part do you feel that your health issues play in your decision to walk away? Is it the health problems that caused you to be so dependent on your H?
You aren't the first person that discovered what they lost was truly what they wanted all the time. It takes something major to wake us up and get our eyes open. Also, it sounds like he has done a major over-haul on his looks. Loosing a hundred pounds is not an easy thing! He had to have looked good to you after that!
Don't give up. He is probably getting looks from women that hasn't paid much attention to him in a very long time and it is feeding his ego. So, try to be patience. I agree with you about the "friend" though. He may really see her as being only a friend, but we women know how the female mind works and she is just laying the ground work.
It is not about what you feel should work in your M. It is about doing the work that gets the right results. Do what works!