This is what my mom told me when I was going through my D with my first H. He had multiple affairs and was abusive but I too couldn't believe he would leave me. I couldn't believe he didn't even want to try. We had 3 kids and spent 11 years together. My mom said that some people don't know how to love. Love is about unconditionally accepting someone and making them a priority in your life. My ex couldn't love like that. With him, it was always about "I'll love you if..." the house is clean enough, we have enough money, you do exactly what I want, etc. True love doesn't purposely hurt the one you love.
I bet if you think about it. Your H has not had this kind of unconditional love for you either. It took me a long time to finally see our relationship for what it was(over 2 yrs post D). I had to quit projecting my love onto him, stop fantasizing over what I wanted him to do. I had to start focusing on me.
This is where GAL is crucial. Have you heard the saying, "Fake it til you make it". It's true. Start doing things that you know you need to do for yourself. Do some fun stuff with your S. Get involved at church or a club. Find a meetup group, book club, cooking class, anything. Whatever you do get out of your house and get with other people. Eventually, you will feel better but you have to have the action first. The feelings will follow.