Bettyboo, it all sounds so so exhausting. I remember feeling the same when my youngest (now 2) was a baby, so if my eldest (9) ever got up, I'd just feel so angry and frustrated! I still do at times now if he gets up (as turns every single light on wakes everyone up!).
But I do think he just needs you, it's so easy to say calm, when you're in the dark of the night completely shattered, your anxiety will be high, his anxiety will be high, you will both be bouncing off each other.
It does sound like you have anxiety / possibly PND. I suffered after my first and it always lingered for a long time. I've actually had counselling this year and the main focus has been to talk about my feelings of frustration towards the eldest, when the youngest consumes so much time. It has helped A LOT, is that something you could do for yourself? Reach out to talk to someone, why it is triggering you so much, and why you feel so sad/angry about it? If you can work on strategies to better channel the frustrations and upsets on your part, the situation itself won't feel as bad and scary for you.
My eldest is the same, sleeping with us isn't a solution, as he's more restless, and doesn't sleep. So I know where you are coming from with that.
I'm not going to offer any wise words of advice for the nights as I'm sure you've tried everything and many have suggested lots of good ideas, but do try to get help for yourself. If you focus on yourself first, your feelings, the rest might fall into place.