I guess you now know freezer paper is not the best if you want to remove the paper!
In future use golden threads paper or copy paper for this type of work.
I would run a chop stick or something similar along the sewn line and gently pull from the sides to seperate the pieces. Freezer paper has that waxy plastic coating on it so this will be a matter for patience to tend to.
take your time and walk away for a while if you have to.
Don't feel bad about this. It is all on the learning curve
peace