The entire game I was actually terrified the final boss would end up being another SH1 thing. Anyways, I had like 79 handgun bullets and 64 SMG rounds and like 13 shotgun shells. Plus 4 ampoules and 1 first aid kit. I ended up using all my health items. Towards the end I think one more hit would've killed me, and I had no health. Plus I had virtually no handgun bullets left, so I was predicting I would die and planning what I'd to finally kill it. Turns out literally my last handgun bullet killed it.
Glorious.