grouchy momma cat. ..

Our young cat got pregnant while still nursing her first litter, she was a very attentive mother. Once she became pregnant with the 2nd litter she began to be very aggressive towards her older kittens and eventually grouchy towards everyone. Now she just abandoned her newborn litter(those that survived were adopted) and is still grouchy. We planned to get her fixed, but will she return to the sweet kitty she once was?

I don't know, but not going through heat should help.