Need Info on Partition of Sale in PA

I recently split with my partner of 12 years and we have tried to sell our house with no luck.

A friend of mine offered to purchase the house through just us with no realtors so that allowed me to drop the price of the house. My friend and I decided that 650,000 was a reasonable offer and that my ex and I would walk away roughly with around 75k each.

He refuses to sell at any price that will get him less than 100,000 in profit. Sadly he just is not very realistic in seeing that in this market there is no way to sell the house and get that much in this market.

How long does this take the process take if I already have a buyer? Would my friend be able to purchase in 3 months? What is the cost? Is it an easy process and could my ex stop it or slow the process?