I strongly agree. Find a lawyer, find a lawyer, find a lawyer. To the OP, if you're in California, I'm happy to recommend mine. Adam Slote of Slote Links and Boreman, slotelaw.com. 20 years back somebody was trying to screw me over; he charged me $500 for a solid "don't fuck around or you'll regret it" letter. They paid up instantly. Since then he's been great a dealing with my startup stuff both as an employee and as a cofounder. And much of his work is in litigation, so if you do end up suing, he's the right person for it.

I also agree that the 1-year cliff is absolutely not standard for founders. Last time I did it, I had a 4-year reverse vest with no cliff at all.