What happens if I stop paying the debt collector?

Location: UsIndiana
Hello! About 2.5 years ago, I received a summons from a debt collector law office that my credit card company was suing me for not making payments on my card. I reached out to the debt collector and settled it out of court. Mutually agreed upon amount to be paid monthly. Since then, I’ve paid my amount monthly; however, I never receive anything in the mail or email regarding my balance. Even when I was a few days late on one payment, I never received a phone call to pay it or a letter in the mail. I’ve tried to call the office of the debt collector law office and never can get through. I called to see how much I still owe, and I have no idea and can’t get through. What would happen if I just stopped paying? Thank you in advance!