A similar thing happened to me when I was on my scooter a week ago. Fortunately for me, the guy got out of his car, admitted fault and apologized. This case may be a little different because the other person hasn't admitted they were at fault...

Basically, it looks like the other driver crossed into your lane while parking. if you were moving forward and hit them, it's possible that you'll be found at fault for not maintain control of your vehicle at all times. if you were stopped and they pulled forward into the side of your car, it's pretty obviously their fault.

Don't go to your insurance right away and hopefully you get the other driver to admit they were at fault. Best of luck to ya, hopefully the other driver's insurance is helpful too!