The main purpose is to not let it affect you. How do you not let it affect you? By being so into what YOU''RE talking about that what she is saying is really of no value whatsoever. There is no perfect response. The above were good, but the underlying frame here is bad. You are thinking in terms of what to say back. Rather, be self involved in your own talk.

Good responses:

"Cool"
"So do I. Let's double date sometimes"
"I have a gold-fish"
"Look, a squirrel!"
*Just keep talking

Or you can also just show empathy. Say "I understand", walk away, then reapproach later.

Or you can say "I understand, you just seemed interesting and I wanted to talk to you. Let's just be friends" - and then you continue gaming as normal. This may actually be one of the best options, as your only aim is to stay in set, so that you can build enough comfort and trust to push things to a sex location, or to end up in one mutually with her so you can escalate.

ok cool

then i start escalating