I so feel your pain! My boy is nearly 4 now, and I wish I'd not been so frightened to co-sleep when he was tiny. I started at 6 months and if I had my time again would do it from day dot.
I joined a few co sleeping Facebook groups, and also the beyond sleep training group - I wish I had found it sooner, because it reassured me that the instinct to be close was OK and natural rather than flawed parenting.
My top tips are sleeping bag for baby (Mine liked to move his legs, so we got one's with legs when he got a bit older) lose the duvet, safe C sleep position for you, tie your hair back, warm cardy on. Also a pink salt lamp, so you can see at night, but it won't stop you both from sleeping.
Mine now starts the night off in his own bed and wanders in to me in the early hours and goes back to sleep. One day he'll stop doing that, and I'll enjoy the space but miss him immensely.
Also, please ask outright for a referral for your mental health, even if you have to find a way to pay privately. I didn't, and ended up with a ptsd diagnosis 2 years later. Looking after yourself and your mental health is the most important thing you can do. You sound like an amazing, nurturing and caring mum who's wonderfully tuned into baby - you'll come out of the fog. I promise.