Please give your opinions on this....?

what is the penalty for a spouse who forges the signature of another spouse's on both the tax filings as well as the refund cheques? My ex husband has been forging my signature on all the tax filings and refund cheques for the last five years as I had never filed before and did not know the procedure that both signatures are required if filing jointly, as I had not been working and had no need to file taxes. However, after the divorce( due to tremendous domestic violence, and an infant being involved in it) I started to work and needed to file this year, that's when I found the joint signing rule for filing jointly, I want to contact the IRS about this but was told they would not do anything as they would take it under "tacit consent". But there was never any tacit consent at all, as firstly the relationship being extremely physically abusive, he had control of everything and I never even knew what was being filed or how and also that joint signatures were required, so I was truly unaware that he was even signing for me!! Secondly , he has been filing jointly even now when we are divorced and claiming the baby, and I need to file my returns, but the signature will vary. I have all the tax filings records with forged signatures which I obtained from the IRS after discovering the forgery and can prove that my signature is forged, I also have the domestic violence arrest records and cases to prove he had control of everything anyways. If I report him to the IRS, will they take any action against him? will anything come of this? He has been encashing all the cheques by also forging my sign and I found that he has not reported his income from overseas, how much is the value of the income from overseas that one needs to report? please advise, I need to know whether I need to notify the IRS but only if its taken seriously by them.