Will onj stop once I stopped prolia. I've only had 1 injection?

Hard to say. There are no conclusive studies or test that link onj to the ingesting of bisphosphonates. The IV form is another story but this also depends upon the type of mouth surgery you are going to have and the skill level of the surgeon performing the surgery.
Possible. Prolia (denosumab) will increase your risk for onj, however unlike bisphosphonates there are studies that show a drug holiday will resolve an osteonecrotic lesion more rapidly than we see with a bisphosphonate. This will depend on the reason why you are taking it, and the dose given. It also depends on if you already have onj. I would see a physician and oral surgeon for close management of onj.