Lack of communication seems to me to be the biggest issue but it seems too late as she has told me she "is not in love with me anymore or attracted to me and how does someone get that back?"
I'm sorry you're here - but welcome!
This one jumped out at me because there's a couple of things - one is what you can answer her: "What do you do if you're watching a fire die down? Run off to find one that burns higher or feed the fire in front of you?"
I think being mysterious would work to your advantage. It can be good if she thinks something is up, but be careful so it doesn't cross into manipulation. Just say that you realized you had gotten a little lazy and you want to take better care of yourself. A man who takes care of himself without overdoing it is very attractive to a woman.
Can you remember anything she used to compliment about you? Scents you used when you first met, particular items of clothing, beard/no beard? Use that and then be mysterious and GAL.
If you're the primary caretaker for D7, have you considered getting primary custody? Have you talked to a L?
M 16 yrs, WH62, P54 3 adult blended kids EA 11/13, BD1 6/14 PA fall 14, BD2 2/15 Piecing 2015, BD3 12/15 Separated 4/16 WH moved OW in 5/16 Divorced 6/15/17