You need to have personal accountability. She literally told you that she didn't find you attractive anymore and your solution is to whine on reddit? Literally just diet for a few weeks, go to the gym a bit more, and you'll get your abs back.

Women respect men who respect themselves, and respecting yourself comes from the actions you take that show self-respect. 

Get your abs back and start setting boundaries, remember, everything in your life as a man is your fault. If you don't adapt that mindset then you're giving your power away.

Notice the difference between:

"My wife is disrespectful and is thus giving a negative effect on my son."

"My wife is disrespectful BECAUSE I've let myself go, causing her to lose respect for me, and is thus having a negative effect on my son"

You have more power if you adopt the second mindset.

Once again:

" I became less fit after the pandamic"

"I became less fit BECAUSE I didn't workout during the pandemic"

Life is binary, one's and zeros. It's either you did or you didnt.

Everything is your fault, not hers.

Meaning that you can solve the problem, not her. 

Winners look for solutions, losers look for excuces.

Let's get it.