When I felt like I was spinning out of control and looking at others for validation and comfort, my therapist advised that I really focus on self-care, emphasis on "self." She advised to do things that make me feel pampered, like taking a hot bath, getting snuggled up in big-collared sweaters or soft blankets, thick socks, and drinking warm beverages like herbal teas. She advocated finding good smells, nice lotions, and bathing myself in small things that feel -- literally FEEL -- good and warm and solid.
She also had me do some "safe place" kinds of exercises and meditations that actually helped after a lot of practice, and still do. This part was hilarious because I have absolutely no patience for this kind of thing, and had to train myself to not fear looking ridiculous or feeling like a dork for giving it a try. Pride and vanity are my downfall.
I second the suggestions of the people that urge you to *do* some things that don't involve thinking about him. Since my AH is gone, I've taken the time to incrementally clean out my house and do some silly and not-silly household crafts and spend time with the kids. Things got really bad when my inability to get past the betrayal sucked all the joy out of the household for the kids, so I had to yank myself back to stability and find ways of interacting with them that was just us, just fun, emotionally safe, and bad consequence free. We go out to eat when we can, and go on bike rides when it's warm, and the oldest and I paint together. We even made cat toys one night.
It does get better, one step at a time.
I also suggest that you at least get a consultation with a lawyer, even if you're not willing to file for divorce. Be prepared to pay the $200 fee, but oftentimes they "waive" that to convince you to come back to them when you file. At the very least, you'll have your ducks in a row, which means you will be better emotionally armed for the next battle.