You can go to r/legaladvice if you want the actual legal steps, but most important, document everything. Take pics of the vermin when you see them, save the emails or texts to your landlord. This kind of landlord seems unlikely to do anything. However, landlords CAN report you to collections agencies for breaking the lease and say you owe them the remainder of the rent, or more likely two months rent, which is what happened to me. You want a paper trail to show that you tried to fix the situation and the landlord did not.