AITAH for not wanting to financially help with my boyfriends kid

My boyfriend (33) and I (26) have been together almost 4 years.

When we started talking 5 years ago he told me he might have a kid. I asked him if he got it all sorted and he told me yes and the lady told him it wasn’t his. (I thought nothing else of it after that) Fast forward to now and he comes to me and says he wants to find out for sure if the kid is his or not. I was pretty ticked off- like dude the kid is 8 why didn’t you get this figured out when you said something 5 years ago?!?! It turned into a huge argument and honestly didn’t know whether I wanted to stay or go. They are going to do a DNA test soon so I figured it was time for me to get my ducks in a row. So aitah for telling him I don't want to be financially responsible/tied to the kid in any way? When I told him I didn't he acted like I insulted his mother. TBH the kid isn't mine, is 8 years old and I at this point have no desire to act as a parent.