OP, I suspect you will find that under the FDR, (Fault Determination Rules), that the insurers are required to file with FSCO and follow, when completing claims, this will be ruled a 50/50 scenario. You were not making a right turn, but attempting to proceed straight thru an intersection from a lane which didn't exist on the other side of the intersection, (Commonly referred to as a bus bay). It wouldn't have been marked as a right turn lane because for all intents and purposes under the HTA, it is not a right turning lane, but a bus bay. The lane which the disabled tractor trailer unit was in is the actual lane one "should" be making a right turn from, (even though we all now in reality people use the bus bay as the right turning lane).
The other vehicle, also made a turn "not in safety" in that he didn't look for obstacles, (even though you NEVER should have been there), the other driver is required to ensure the path is clear. The fact that neither of you have been charged by police is immaterial. A police charge does NOT affect insurance FDR's.
It appears that you don't have the disposable income to pay for the damages to the other vehicle and also have purchased accident forgiveness. In this instance, it is in your best interest to file the claim, and be done with it. Just be aware, that this means you can not purchase accident forgiveness coverage at renewal, (depending upon your insurer's own rules it could vary 3 - 7 years before this coverage can again be purchased, same as the time period you would have faced increased premiums if you didn't have that coverage.
In the end it will likely cost the other driver MUCH more when his rates go up for the next 3 - 7 years on his BMW, (or whatever status symbol he buys next..lol)
As for "amending your drawing" on the police report, this is not permitted. At best they "may" allow you to file a supplementary report, with the amended drawing attached, but the original report will remain on file with the original drawing. This is why when filing an "official report" it is best to take your time, (once you begin filling it out there is no time limit you can rush and do it in 10 minutes or you can ensure you have it right and take 120 minutes..lol