Breach of contract/unpaid commissions - about to do mediation. What to expect?

Location: California. I had a contract with a manufacture to sell their products. I sold a lot. I was paid commissions only. I decided to part ways in January. I found a better manufacture to partner with.
I’m owed about $200k, which the owner is disputing. We’ve sent multiple letters, including a demand letter, and our attorneys have talked a couple times. Looks like this may be headed to mediation. My lawyer says it will cost about $4-$9k and says that “this is definitely the best solution and will definitely get me the most money”. So what should I expect in mediation? Will just the lawyers talk, or will I also talk? Will I have to see or talk to the other attorney or the owner? Also, is my lawyer right? Is mediation really better than just going the distance with a lawsuit? I feel I have a very strong case, so I don’t really want to settle for less than I’m owed.
If mediation talks fail, then what?