What do I do?

I lost my grandfather a week today, I had been caring for him and my late grandmother since I was a teen, grandmother died of dementia last year, grandfather became suddenly Ill with urosepsis, less than a week later, after being told he was improving, he is dead.
I am doing my best to support my family with this though I bare much anger towards certain members etc…
I’ve had little sleep for days and feeling stressed, my partner Insisted we go away for 2 nights , 2 nights ago Whilst away, i find myself on the motorway with little recollection of getting there!?!?! I had woken from a nightmare but couldn’t shake it off, I remember feeling panicked but I don’t remember getting in the car, I was flashed on the road and I absolutely panicked and pulled into a service station to gather myself.
I was terrified! I pulled self together and drove back to hotel.
My partner was none the wiser, he takes sleeping tablets we had a strained day and had argued, after telling him about what happened he has since been insinuating that I knew what I was doing…!?
I can’t work it out. I’ve no support, I’m scared of it happening again or what ‘it’ was.
Can anyone relate

Hello, your post is distressing to read and I think you should ask for help from your GP. I know it’s a big step but you were in danger as well as being dangerous to others.
I have heard that many people have things like this happen to them whilst grieving and doing things in their sleep due to being totally stressed. It must have been such an ordeal and very terrifying and you certainly don’t want it to happen again.
I hope just by writing about your problems may have helped your stress levels a little.
Take care Sxxx