You can say this to someone who you've helped out a lot, when they do something like complain about you:
A: You never take me out to eat.
B: After everything I've done for you, you complain about me not taking you out to eat? I can't believe you.
Or if someone lies to you:
After everything I've done for you, you're going to sit here and lie right to my face!?
This is a really emotional, dramatic expression. Use it when you feel really annoyed or angry with someone.