Collecting $$$ for large repair from tenant

[Ken Goodman]

My tenant is responsible for damaging the bathroom floor and dining room ceiling below through long term negligence. This will cost thousands of $$$ to repair properly.  I have only one month's rent security deposit, not nearly enough to cover the damage, and insurance won't cover this.  He is disputing his responsibility, but the lease is clear, he's responsible for interior repairs and negligence.  What is the best way to collect the money?