Question About Barrier Removal. Do I Have To Pay Or Does The Landlord Have To Pay?

I am being sued by a disabled person because I have a step outside of my restaurant. He cannot go over this step with his wheelchair.
I have leased this building for about 5 years, but the owner of the property has been operating it for a very long time (some time prior to the 1990 American’s with Disabilities act).
The guy suing me is running a scam where he is suing dozens of businesses who have a barrier such as a step infront of their restaurants.
Under the law, the building is considered a joint operation between myself who runs the retaurant and leases the property, and the owner of the property. It says it is between us to decide who pays for the barrier removal and this guy’s monetary damages he is seeking (no less than $4,000) for mental distress and “embarrasement”. It was not readily achievable for me to put the ramp up when he first requested it, but I have since installed the ramp. While the ramp was not yet installed, I took his order at the door and brought his food to him outside of my restaurant. This is deemed acceptible under the ADA regulations as an “alternative” means of providing him service while the barrier removal was “delayed” due to financial reasons.
My question: The property owner is saying I, the one leasing the building for my restaurant, am the one who should incur the full cost of the barrier removal and the monetary damages this man is seeking. The law says that it is between the two of us to decide who pays. Since he owns 50 properties, isn’t it more “readilly achievable” for him to pay for at least some of this than I, who make only a marginal income from my business?
How do I go about getting him to pay half or more of the cost? Do I have to take him to small claims court?
I would like to do this without a lawyer, but should I retain an attorney just in case, even though it will bring additional cost to this whole matter?
Edit: I make a small amount each year (roughly $50k), and only have 5 employees, all of which are my family members.