Complications with resignation

Hey all, I'd joined a startup in May 2022. Before joining when I had a detailed conversation with the CEO and founder he had promised many things. Primarily on these was a notice period of 45 days, but he mentioned 90 days in the contract. But he has assured me that he'll not enforce it as it's practically impossible to serve a notice period of 3 months. For the last few weeks his attitude towards the whole team has drastically changed and the working conditions are very toxic. He favours some people and hinder others tasks and later questions them for low productivity. He has us working on cracked commercial softwares in an isolated PC and don't have proper safety precautions for the chemicals we handle. I suffered depression due these work conditions. Now I've made my mind to leave the company as it's affecting my mental health very badly. I wanted to ask if there is anyway of enforcing his verbal commitment for the notice period? I'm worried because all the other people who have resigned were treated very badly. He even refused to provide background verification for one of the previous employees. I as well as other team members don't trust him personally. Thank you