Claimed as a dependent?

My boyfriend and I have been together for many yrs.We have 3 sons.We are not married and always keep things seperate.I own my home and property and he owns the land next to it.We each have seperate mailing addresses.When we had our 1st son I claimed him on my taxes for the first few yrs.Then when we had our other 2 kids,I stopped working to stay at home. Two yrs ago he went to file his taxes and claimed me.No biggy...til I noticed he signed my name.His CPA let him.This last yr he did it again.Forged my name.So basically I am curious about what I can do now.If I go back to work this yr how do I now file my taxes?I had someone tell me that since he claimed me (filed jointly)we would have to get a divorce or show seperation.This sounds nuts since we are not and never have been married. We are still together but I never gave permision to file jointly.I have copies of his last 2 income tax returns with my signature forged on both of them.