I don’t understand why nobody has mentioned this yet, but you’re not supposed to drive over the solid line. The dashed line /solid line combo means you can cross it from the dashed line side, but NOT the solid line side (so the other car is ok to get into the turn lane from where it did and then make the left turn when traffic permits, but OP isn’t).

This would make it clearly OPs primary fault as neither of the other car would expect them to be turning into the turn lane from where they did.

Is this somehow different in the US?? I’ve seen most turn lane here in Canada split like this. It shouldn’t matter where the actual turn you need to make is in relation to the lines, you follow the lines and if it takes you too far you make a U.