Some of the Viejas are not particularly docile, I find them to be more aggressive than many of the so called volitile cichlids like Parachromis. Eating fry and killing a mate is also normal. Pair bonds are often fragile and unless there are other fish in the tank to solidify the bond, or to distract the male after spawning, his mate can become the target.
Nets are also not great places for fry, the parent can easily suck them thru the mesh.
Normally first two or three spawns a pair makes is eaten.............
It's a learning curve for you and her, you'll have more tricks up your sleve next time. It isn't unusual for the first few spawns to be eaten though. IME Plecos are bad news with eggs and wigglers. I would let her try a few times to get it right sans pleco before pulling and raising the fry in a seperate tank unless you really need the fry. The parents when able do a good job raising the fry.