That's right, the cops can't determine who's at fault. That stuff is done by civil law, and cops don't do civil law. That decision is made by insurance companies and their teams of lawyers.
Now for the part you're not going to like.
If you were leaving a parked position when this accident happened, it was your fault. When you're leaving a parked position, even if you're not reversing, you have no right of way over anyone else. Your insurance company is going to accept 100% liability on your behalf (yes they can do that, it's in the contract) and be done with it.
If you were hit while parked, the other guy is probably going to say you were pulling out from a parked position anyway. That means it's going to go 50-50 with the liability, because you don't have video footage or an independent witness.
So like your options include walking or riding a bicycle.