My dad is making me miserable

It is just shit and you are correct there is no smooth answer where others who are equally conditioned by his shitty behaviour will behave in “normal” ways if you respond to it.

I strongly suggest you read Educated by Tara Westover. It is an extreme version of your experience but it will help you stop feeling alone in this. My family has similar patterns. I walked away a long time ago for my sanity. DHs family is more or less identical to yours expect FIL was physically violent and exhibited a tonne of coercive control. We have fantastic lives now but we have nearly fully separated from family to achieve that. Sometimes these situations just cannot be fixed.

I suggest you start to train yourself to stop taking responsibility for him and learn to deal with the backlash rather than learning to deal with him.

OP I could have written your post word for word right down to the 'oversensitive and prickly' and the ' I get tricked by his apology into relaxing and then it comes back again'. I read your post aghast because it was so familiar.

I feel for you as it is so bloody awful. It feels like a trap.

This point of yours is key I think "I wish it was that easy. It's the entire family fallout that would follow. He's already triangulating me against my siblings. To be fair they aren't buying in but it's so difficult."

This is the Fear part of FOG.
You are only wanting to set boundaries and ask for decent treatment - you're not asking for anything unreasonable and yet you are afraid your siblings will side with him (even though they are not).
Work on this. Talk to your siblings really openly and honestly. Ask for their help. Tell them how it is. Whilst the threat of wider family implications hang over you then you are as isolated and in your dad's thrall as you were when you were 7.

Fill your space. Set your boundaries. Involve your husband and the most straightforward, decent people in your family. Set boundaries.

One smaller/easier thing that worked with my dad was to only ever talk to him about banal stuff - the grey rock thing. I would have a list of nonsense I would talk to him - dogs, football, weather, my friend's new house, my veg patch. At the first sign of him going off on one I would interrupt with, 'OH, remember I told you about Toby, well he chased his ball into the pond in the park on Tuesday............'. The distraction was enough to work.

My dad died suddenly and it all stopped. The relief was intense.
On reflection there was no good way to handle it. He could be a right arsehole.
Put yourself first. You'll never regret it.

You've done nothing to deserve this shit. Don't put up with it.

Oh OP, I feel for you. Slightly different circumstances for me and the other way round - I can't stand my 'd'M-she makes me feel like shit/irritates me to death, nearly every time I have to spend any time with her, but like PP has said, I have to keep some contact otherwise it will (and already has) affected my relationship with dSibling. We had approx 6/7 years of caring for Ddad until he passed a couple of years ago and the care was 24/7 (couldn't be left for more than 5 mins at times) and I felt coerced into a level of care I shall never forgive her for. She has also shattered my happy memories of dad because of that. As soon as he died, she 'aged' and now can't drive and leans on us more and more. So we rolled from caring for one parent, straight onto the other. I know some people have it worse but it is positively the most difficult situation I have ever dealt with and I've been through a lot in life. The whole family dynamic has changed now dad has gone-he was the fun one, the glue that kept us together and the buffer for her irritating and upsetting projections. One thing I have learned and that has helped, is to stop trying to please her all the time - I just agree with everything she says (advised by old neighbour) drop the mental guilt when I can (really hard when it's so bad it's got you to talking out loud to yourself) and I've also learned to say no. (I also tell her to fuck off a lot in my head) I'm not responsible for her happiness and I think I'm suffering from caring fatigue. I love her, but really, really do not like her personality and manner. As the old saying goes, we can choose our friends, but not our family. Sending peace OP 🙏 X

You're an adult.
Not a scared kid anymore.
Grey rock technique - he'll get bored eventually when he doesn't get a reaction

You are giving him too much power .

I get it. We do manage their behaviour. But we will be miserable and exhausted if we don’t do better!
Can you not be non confrontational, just very matter of fact? He doesn’t want to Dad. He’s avoiding arguing with you, Dad.

Have you read about Grey Rock? It’s the only way to cope, imo. Deflect deflect deflect, but without anything that gives him or your siblings purchase. Like being a slippery bar of soap!

And believe me I sympathise. My mother is the dad in your situation.

You really do need to stop ‘managing’ his behaviour. I know you don’t think you are, but you are. The obvious answer when he raises it would be, ‘Don’t be ridiculous Dad! You behaved appallingly and DH doesn’t want to put up with you. And he doesn’t have to!’.

Followed by as many repeats as necessary.

Your situation is very similar to mine minus the dh fallout as I’m single but my father’s behaviour is pretty much the same as your fathers, my mum was the patient soft enabler who shielded us from the worse of his tantrums and spitefulness. Since she has passed he has become almost unmanageable. I still have to see him regularly otherwise the huge family fallout from it would destroy my relationship with my sibling. My father is 80 this year and I can honestly say I hope he doesn’t live much longer. I love him but I do not like him one bit. I will return to this thread later op I have to go out now but you have my absolute sympathy. Just remember though you aren’t responsible for your father’s behaviour, it’s all on him how he handles life.