Left Hand Turn

I need some help, Please

My insureance company said I was about 90% resposible for this accident.

I was at a traffic light trying to make a left hand turn, I had a solid green light. The other driver had his right turn singal on and was in a turning and was in the a turning lane.

When I saw this I proceded to make my turn, the person that was in the turning lane veered off and went straight. This is when the colliision occured.
When making a right at this intersection you must be in the turning lane. If you go up to the intersection you must go through it (there is also a curb that directs you to the right, Am I painting a pretty good picture?).

My insurance comany says that I am at fault, since he had the right of way in the turning lane I should have been aware that he was going to veer off and go straight. I do not see how this could be possible, if he is in the turning lane with his singal on.

I also was told that a green singal means that I must yeild to all on coming traffic. But does on coming traffiic also mean that traffic that is procedding to make a right hand turn.

I would like to know if I really am at fault?

I would like to know if I should take my insurance company to arbitration.

Please Help,
Thanks

Yes, on a green light you have to yeild to all on coming traffic when making a left hand turn and yes this does mean you need to give the right of way to all people turning right. People turning right are considered on coming traffic. I just looked this up in my state driving book.
-Hope this helps