I realize the answer to this question will be very personal but I will throw it out there for you to maybe at least think about.
Have you spoken to your C about how you are allowing your emotions to guide every aspect of your life? IMO that is the crucial element that must be addressed for your own mental well being. If it is not addressed things will continue to fall apart for you... your home, the other R's you have, your mind and body and your job.
Now I know it is NOT easy to NOT be emotionally reactive. What I have learned (granted the hard way!) is being emotionally reactive is okay when you learn to control how long the incident stays with you. My H sent me something in the mail the other day that was very upsetting to me. I was hurt, angry, pissed and all that good stuff. I did cry and felt like crap but only allowed myself to be feel that way for 1 hour.
I guess what I am confused about is you have already lost your H for now. He is living with OW and about to have a baby with her. His R with you is based on a child the two of you have. He backed out of coming home a while back and for now has made his decision. It is all beyond hurtful but the reality is (for now) you have lost him. You emotionally letting go and beginning to rebuild you is not going to change the current situation. Actually, it will change things because you won't be so paralyzed.
I really do say this with nothing but concern but if you continue on this path your entire life will fall apart in ways you didn't think possible. The emotional distress and anxiety I allowed to control me almost resulted in me losing my home twice, losing my biggest client of almost 8 years, losing 50% of my hair, losing so much weight my body rebelled on me and sent my lupus into overdrive, I almost lost a kidney and made some VERY stupid choices with my legal case. Once you (me, anybody really) gets to such a state of distress things start to domino fast.
I know it is hard and you probably feel like punching us all in the face when we keep asking you the same thing but why have you not made a goal list yet? It could be as simple as making goals for the next 24 hours. Small and attainable goals that will give you some momentum to make some more.
Do you understand emotional thought stop techniques? I never in my life had heard of such a thing until my life spun out of control. They are hard work but the key is they *do* work.