Thank you all I read all your messages in the night and they helped so much. I didn't want to respond then to limit screentime as advised.
Reading that it was just a blip and I would be OK really helped my catastrophising brain, as well as hearing to just aim for rest not sleep.
I kept telling myself this, listened to a podcast and eventually did fall asleep. I only got half an hour before my brain woke me up but it took the edge off and after feeding baby I got back to sleep fairly easily which has taken away a lot of the fear. I think I got about 3 hours.
I find looking after my newborn quite soothing this time, it's really my toddler waking that triggers the anxiety , probably because they usually sleep very well so when they don't I feel like it's all going wrong and I am completely doomed. Whenever they made a noise in the night my heart started racing and I couldn't breathe. When they were a baby was when I first experienced anxiety/insomnia and I was so happy to think I had avoided it this time...
I get that DH should deal with toddler wakings but they have been such a mess since the baby was born I knew they would kick off and cry longer unless I went in. As it is I just walked them back to their room and they went back to sleep quickly. Wouldn't have been an issue if my anxiety hadn't then kept me up for another 3 hours afterwards...
I will speak to GP about something that can be used when breastfeeding in case it gets bad again. As a PP said, I probably won't even need to take it but just knowing the option is there will help me massively. As I feel so trapped with breastfeeding knowing I can't go away for a night if I get to breaking point, and can't take any medicine to help.
In general I just need to stop thinking about sleep so much I think. I had a csection and am housebound so my days have consisted in sitting there holding baby and trying to nap for 3 weeks, then going to bed at 8pm with baby to get some sleep. I have zero other distraction or interaction to busy my brain with, and am so sick of the number of hours spent in that bedroom trying to sleep. Hopefully once I can get out and about I'll feel more normal again.
Thank you all so much again, your support made all the difference so I didn't feel so lonely and it got me out of my own brain. So reassuring to know others have been through the same and came out the other side. I think DH thinks I'm weird and make my life hard for no reason, he doesn't get it at all, so it's good to know it can be fairly normal in the postnatal period.