My girlfriend said something during sex that upset me and I'm going to tell her.
Can you tell me what she said that upset you?
I'm so tired of hearing her bragging about how good she did.
This could be taken the wrong way and if she think that you're insulting her sexual abilities then it might harm your relationship.
But she made fun of me while bragging about herself.
Your girlfriend should never have insulted your sexual abilities especially while building herself up. You deserve to be treated with respect and tell your girlfriend how you felt about her comments is reasonable.