PPD can cause sleep issues and sleep issues can really do a number on PPD. You are dealing with a lot right now! Is there any way you could nurse Jade at 10 or so and then hand her off to her dad so you can go to bed? He could bring her to bed for her feeding at 1 or so and then you wouldn't even have to wake up fully? I know with breastfeeding it is tough...but the sleep you get before midnight is really important. You could even go to bed at 8 and have your boyfriend bring her to you for feedings. It would not be forever. Even a week of more night time sleep would help. For me, I needed to take meds, eat right, take fish oil, exercise, sleep a lot and talk to a therapist. But I didn't have 4 kiddos to take care of. You are pretty awesome, PPD is tough and you are still doing what you need to do to take care of your kids.
This is the approach that worked best with my family and support system: (thank you therapist!!) I was pretty matter-of-fact and told them that I was suffering from PPD and that I was being treated. Getting adequate sleep (but keeping up my milk supply), good nutrition and exercise was of utmost importance and I would need a bit of help with the baby and other stuff for a little while. My PPD kicked in right around 2.5 months and peaked at about 4 months. I needed a lot of help and support for about 3 months. After that I started doing a lot more for myself and my family because I needed to feel competent to fully recover. You seem to be really competent already, you probably have some confidence in yourself as a mother (as you should!) As well as some routine. Routine was really important to help me feel on top of things and less stressed.
How long have you been on medication? Is it a medication that has worked for you before?
Are you taking any supplements? Fish oil (look on the bottle for the amount of EPA, my Dr. recommended 800mg a day) magnesium citrate and D3 have all been mentioned on this forum as helpful and I took all 3 (still do, 3 years later)
Have you seen someone about your C-section recovery/pain issues? Physical pain puts such a huge strain on our mental health. You are an experienced Mama, you know that that having a baby and nursing can make sex painful, but if your pain is more than that really push your Dr. for help. You are not getting enough sleep, it's really hard to want sex until you are rested. BUT it shouldn't hurt more than "normal"
Once you are getting a little more sleep at night and the weather warms up, you could take long walks with Jade after you send your older kids off to school. Fresh air, sun and exercise will make you feel better...
So, maybe try talk to your boyfriend in a calm manner about your condition. (As apposed to talking about how stressed and hopeless you feel, he can't do anything right now about THAT, but he can help you get more sleep....) Even normally mature, supportive men can become overwhelmed by the extreme anxiety, sadness and hopelessness of a partner suffering from PPD. Tell him what you need and tell him that you will get better. You will!
I hope you feel better soon Mama!
Edited to add: I was also scared to be alone. For the most part I tried not to be. Is there anyone who can keep you company during your "alone" hours? I am an introvert, so the lack of alone time was a strain, but helpful for those early scared-to-be-alone days...