AIO my girlfriend just told me I have a small penis

So right away I’ll just state I’m a grower not a shower, but my member is 6” erect. I’ve always assumed this was pretty average.

Tonight I met one of her exs. Pretty tall guy so I jokingly ask her is he bigger than me (my mistake don’t ask questions you don’t want to know the answer to) and she says yes.

I asked a yes or no question and I honestly wouldn’t have given either response a second thought, what bothered me was her follow up statement “but to be fair your penis is kind of small”

As you could imagine that statement was not just a kill shot to my ego, but makes me start questioning a lot more than it should about our relationship.