Throwaway bc my partner knows my main. 

So my partner's brother is in a death metal band. For some reason this type of music triggers my anxiety. I have absolutely nothing against it, I love music, but even going into Hot Topic when there's metal music playing triggers my anxiety, I can't imagine going to a concert at an enclosed venue with it playing that loud for any length of time. He has a concert in our city (he's from out of town) Saturday night and my partner plans to go to support him, and I don't know how to communicate to him that this would be too much for me to handle without it seeming like I'm just using my anxiety as an excuse to not go. And my dumbass told him I'd go back in January, secretly hoping he'd change his mind about going himself. So he's now bringing up that I never keep my word and that he "figured" I wasn't going to actually go. 

The thing starts at 9:30pm and he's the 5th band, starting his set at 12:45am. We live in Austin and this is downtown which also gives me anxiety, all the drunk drivers and a non-0% potential for shootings in the back of my mind, I know those might be dumb things to bring up but this also influences my anxiety around the whole situation. 

My partner is always complaining that I don't ever want to go do anything, I'm boring, everything stresses me out, and also that I don't like his family and don't ever want to see or support his family. (For context we've been together 4 years and have lived together for 3). 

Looking for advice on what others might do in this situation, and how to explain without it seeming like I'm just using my anxiety as an "excuse". Also wondering if anyone else's anxiety gets triggered by metal music or loud concerts in general.