You could start by directly asking her and also reminding her that forgery is a felony. It is possible, however, that she did not forge your name. It is possible that the bank accepted the check for deposit with just her signature alone. If that is the case, that the bank may be on the hook, as well. That would depend on whether banks must get both signatures (which I think is the case) or whether one is OK. I honestly don't know but I think both sigs are needed. The bank where the check was deposited should be able to advise you as to whether both signatures are needed for a check which is made out to two parties. You would then have a case for forgery - which is actually a big deal, all things considered.
