I've been with my husband for 15 years, since I was 22. We have two young children (2 and 4). He left me and we've been separated for 3 weeks now. I begged him to work on things but he's just done. The pain is absolutely unbearable. I wake up in agony every morning and all day it is unbearable, I can barely function, I'm a shell, a zombie. I'm also dealing with health issues, I have kidney drains in for the next 6 weeks and then will have a major surgery, so currently my ability to do "self-help" things like exercise, go out, go on a retreat, etc is severely hampered. I feel I cannot deal with this pain for much longer, it is too unbearable. I speak to friends, a therapist, my mom (who has since moved in with me to help with my physical issues), and nothing helps. Nothing. I'm in unbearable emotional pain. The house makes me sad, it was our house, and now it feels hollow and empty and full of memories. Doing anything with the kids makes me sad because we used to do those things together as a family. I don't know what to do to stop this pain. I'm forced to still talk to him about the kids, it's literally hell on earth. I wish I could flip a switch and not love him anymore and not care. I can't even explain the pain I feel daily.
That all sounds very awful, your world has been flipped upside down. It's going to be hard for awhile. There is no perfect answer that is going to make everything better.
Right now, one of the best things to do is breathe. Then try focusing on one of your senses for about 10-20 seconds. Calm your mind and then be present in the moment.
You are going through grief and loss over the relationship. The children are too young to truly understand what is going on but they know that you are not okay.
Remember they need you. You are their rock. When they are older, they might not remember specific events taking place now, but they will remember the feeling of the emotions. Focused on one moment at a time.