Or am I being a dramatic idiot who needs to get a grip
I think you need to understand that feelings are allowed, whatever they are. You're allowed to feel like you want to kill someone, or gouge their eyes out with a spoon. You're allowed to feel anything at all, because there are no rules, and there is no guide or authority about what feelings we 'should' have.
If you were abused by an ex, that means you will be more sensitive to certain things. Having sensitivities doesn't make you 'over-sensitive', because there's no 'correct' level of sensitivity. If you'd been bitten by a dog, you might have sensitivities around dogs, but it wouldn't be 'over-sensitive', it would just be part of you, that people who cared about you would take into consideration. And if they didn't, that would be them being insensitive to you.
Have you told your partner how you feel? Because if not, then you're at risk of being the bitten person who doesn't mention their dog sensitivities, and then is offended when someone simply doesn't guess their feelings and takes them to the kennels to look at the puppies.
Calling yourself a dramatic idiot (or being willing to entertain the idea that you are one, just for having feelings) shows a low level of self respect, as does having a relationship with an abusive partner. What was family life like for you when you were growing up? Did your parents teach you that your feelings matter? Did they respect you and listen to you?
You've learned somewhere that your feelings are 'dramatic' and 'over-reacting'. Put simply, feeling can't be either of those things. The way you choose to respond to them can be. Calmly saying 'I felt really unsupported earlier when that tattooist kept criticising me, and you didn't say anything to back me up' is very different from 'You didn't have my back, you unsupportive arsehole!!' Share your feelings with your partner, in a way that respects you and respects him. Find out from his response if he's supportive of you in the way you want him to be, and work out from there if you still want to be with him. Drop all this 'Am I somehow awful?' stuff. You're just a normal person, with experiences, and feelings.