Pretty Sure My Partner Was Still Married When He Married Me - What To Do

Throw-away for reasons. I have supposedly been married for a long time. Like more than two decades. But I’ve recently had a giant wake-up call that my husband has actually been lying to me basically every single day of the entire time I’ve known him. I confronted him about part of it before, and said I really needed to know if he was married because it could bite me in the a$$ if he was still married when we got “married.” He swore up and down he wasn’t. You know how this turned out, right? I don’t know what’s true any longer. I’m almost positive he actually was in fact married to the person, and he married me years before his divorce was finalized in a different state. We own a home together and have been filing taxes jointly all this time. We raised two kids. I don’t know what to do. Part of me thinks he is doing this to keep his options open so he can just up and leave like he did to his two previous partners, but this time he won’t actually need to get a divorce. The other part of me says that he’s a narcissist and a sociopath, and he just thinks the law doesn’t apply to him. I have some money stashed away in a bank account, and I’ve been the breadwinner for most of our time together. I haven’t said anything because I don’t want to act without thinking. He also has an erratic temper and he’s gotten more paranoid. I’m not thinking terribly straight right now. The kids are grown and gone. What are my options? Thank you for any help you can give me in clearing my mind and making a plan