re: $110 medical bill in collections: pay or fight?

I've got a benign tumor in my brain. Blood work often, injections weekly, MRIs biannually. Needless to say my bills are sort of all over. I had a very open conversation between the hospital and doctors office. I will pay all of my debts, but it will be on a payment plan, and the minute you send me to collections I will completely stop payment. My credit score is well into the 800s, I already have a low mortgage rate, and all vehicles I own are 2nd hand . It's forced the billing to consolidate my bill every few minutes which makes it much easier to keep up with instead of receiving 5 different bills every month.