How do you know if water is really in your motor. What else can I do? on 1998 Buick Park Avenue

My car stopped running. I needed a radiator or a radiator hose.Someone suggested this guy I don't know & he says i have water in the motor. He showed it to me but I don't trust him b/c I have other parts to my car that I spent a lot of money on.

The oil will be a milky color and over full... Is it loosing antifreeze but you see no external leak(s)??