The other driver is 100% at-fault for the collision if he tried changing lanes. You should inform your insurance company of the accident, and describe exactly how it happened.
Police don't necessarily assign fault for collisions, they're already pre-determined through 'Fault Determination Rules' under the Insurance Act.
http://www.ibc.ca/en/car_insurance/docu ... -rules.pdf http://www.e-laws.gov.on.ca/html/regs/e ... uote]Rules for Automobiles Travelling in the Same Direction in Adjacent Lane
10. (1) This section applies when automobile "A" collides with automobile "B", and both automobiles are travelling in the same direction and in adjacent lanes. R.R.O. 1990, Reg. 668, s. 10 (1).
(4) If the incident occurs when automobile "B" is changing lanes, the driver of automobile "A" is not at fault and the driver of automobile "B" is 100 per cent at fault for the incident.
Text alternative: In the third type, automobile "B" has moved toward automobile "A" and the passenger side of "B" has struck the in driver side front of automobile "A".[/quote]
Inform your insurance company right away, so you can take the necessary steps to get your vehicle fixed.