After having an abusive relationship for nearly 20 years from the age of 16 how do you figure out what is normal
You don't. You recognise that whether it's trauma or intuition, or anything else, if it doesn't feel good for you, it doesn't feel good, and you distance yourself from the cause of the not-good feeling.
Otherwise you're in the position where something might be very common and regarded by most people as 'normal', and you feel like you have to put up with it, even though it feels crap to you. Like having a partner who goes clubbing a lot. Or who spends his evenings gaming. You don't have to bow to the authority that is 'normal'. You have to respect your feelings.
A little story: My friend had a new boyfriend, and he liked to affectionately stroke her arm when they were relaxing together. Perfectly normal, right? But my friend was sexually abused as a kid, and her abuser used to do a similar arm-stroking thing as a prelude to abusing her. So, because of her trauma, which she respected as being part of her, she asked her boyfriend to stop. He said 'What I'm doing is perfectly normal', and carried on. So she dumped him. Not because he did something that wasn't 'normal', but because she has specific, abuse-informed boundaries, and he didn't respect them, even when she stated to him clearly how she felt.
If you're not comfortable with someone, you leave. You can deal with your trauma separately, but even if this is a trauma response, you need to respect it.
Use your feelings as signposts: if something is good for you, it feels good. If something feels bad, that's a signpost to move away from it. 'Normal' doesn't come into it. It's like food preferences. It's 'normal' to like broccoli, but does that mean that you should eat it, even though it turns your stomach? And if it turns your stomach because you simply don't like it, or because you were abusively forced to eat it in the past, does it matter? You can deal with your broccoli trauma responses later, but, for now, don't feel like you need to be shovelling it in, because of what's 'normal'.