AS did that to me last year, but he wasn't aware of how close attention I paid to my bank accounts. I called the bank the next day, they admitted it wasn't my signature on the check and removed it from my account.
As soon as I realized AS forged the check, I made him go into the bank, tell them he stole from them/me and pay them back. He did NOT learn his lesson, though...continued writing bad checks of his own, for several months.
Now that he is recovering, I just had to pay $1000 to a collection agency to cover all those bad checks.
I thought about calling the police when he did it to me, but I'm glad now that I didn't. He's clean and trying to get his life back together, but can't get a job because of a DUI from 2003. If I had called the police, he would have forgery on his record too. That would have made it even harder on him now trying to find a job.
So basically, I have no answers for you, just my story and how it ended. We can never know for sure if our decisions our correct. I try to follow my instincts and HP, if possible. And I find it always good to "sleep on it" for any serious decision.
Hugs!