Renegotiating a contract

[Terry Royce]

I have a contract with a seller, the house may need more repairs than originally thought.

Asking price was 160
FMV in as-is condition 170-180
ARV 220-240

My price 123
Original estimated repairs 20-25
New estimates 30-35k
Roof and asbestos siding may need work, and I was unaware of siding being asbestos

What are some tactics I can use to get the price down?
I would like to be in the 117-119k range

This will be an owner occupied home.

Thanks for any tips!