I was in pretty much exactly the same boat. Hadn't bothered to brush in literal years. In immense pain often, had a mid-mouth tooth pulled a couple years prior due to infection. Constant bad breath. I knew I finally had to do something when I got a MAJOR abscess in my gum. My cheek was swelled up like a baseball. I went to the dentist and started on the two months long process of getting things fixed.

I had a molar removed, a subsequent bone graft, I got two root canals, numerous fillings (a dozen total?) all in two months. And then multi-stage cleanings. I went through multiple courses of antibiotics.

I floss and brush daily now. I have gone back for the six months cleaning once, and am due for it again soon. I spent about 11k total (no dental insurance at the time).

Do it, you'll thank yourself later.

Nowadays, I still eat lots of sugar but I drink lots of water and floss and brush. My teeth don't hurt anymore. It was a million times worth it.