Hint 1: Try using the search function in this forum. There are tons of threads about fixing old cabinets, T-molding, Bondo, painting, and everything else you'll need to know to fix your cabinet.
Hint 2: Google is your friend. If you type 'T-molding' into Google, you'll quickly find a place that sells every size and color by the foot.
Hint 3: The sticky threads at the top of the page contain lots of good information. You might want to start with the "water damage" thread...