a guy speeding on the freeway wasn't paying attention

to the slowing traffic- slams on his brakes leaving skid marks as he slid from behind me into the left lane- he overcorrected left then jerked right overcorrecting again -leaving more skid marks- and hit me- in my lane- in the rear tire, door and quarterpanel causing my car to spin twice -who is at fault? I know it seems obvious but SF declined to pay the claim-TEXAS