I think my dad is cheating on my mom
Why do you think he is cheating on her?
Because I saw him flirting with one of the local waitresses
I understand your concern, but you shouldn't put yourself in the middle of their situations. If he is cheating on her then the truth will come out eventually, and they will work it out between themselves.
But a breakup will hurt them by sabotaging them financially. I will go get a part time job at my local Walmart.
It's great that you are being proactive and eager to help out financially. However, you may be causing yourself more worry than necessary. It would be best to let your parents work out any tension between themselves.