Big, big hugs.
1. Talk to your doctor. It sounds like PPD to me. I took Zoloft with both my kids and breastfed. There was a great study in a big-time peer reviewed journal that measured med levels in the milk/babies and several antidepressants were practically undetected--e.g your body metabolizes them and they don't get passed over.
2. Ask for referrals to a therapist. You really need to grieve for and process your child's birht experience. That is really tough. And it makes sense that you would be feeling it now that the CRISIS has passed. I can totally see that.
3. Exercise. yes, it helps. But you have to be able to get out of bed to do that!!!! There are lots of great things you can do for self care and a therapist will help you identify things to do. Some things are: 1. Get more help (sitter, DH, etc) 2. Get outside with the kids every day. I sat in a part and BFd DD while DS climbed on the equipment and played in the sandbox. It was shady so DD didn't overheat and DS wore himself out! 3. Try to eat good food--e.g. nutritious insteand of the junk food that I often found myself eating! 4. Get some perspective--it will get better etc. Start with baby steps. Right now everything will be overwhelming.
Good luck!! Recognizing that there is a problem is the first step!!