Jeff sorry your going thru this emotional pain I recently have a similar situation after 7 year relationship.
No more on off one foot in one foot out is what it sounds like.
I stopped trying to figure my partner out I let go with Love and focus totally on my life, in counseling, learning Unattachment by Buddha studies & wish her to be happy.
On the surface when one just turns on their loved ones like this I find it to be very immature. They’re not being open honest, up front They’re Not Being Accountable!!! & maybe not capable but ” They need to be responsible for their actions” & see how they effect other peoples lives & you need to focus on your life & your sons life. Counseling is good as a couple & if she doesn’t want to go best you go alone & work your way to a Happier Life for you & your son.

I wish you both find your path to happiness especially for your son.
Ps when family notices I say “It so much better for me this way” we were on separate paths

Wishing you peace & happiness