I asked this girl out for a cup of coffee and we exchanged numbers. I texted her telling her wednesday at 2:30 because it's the last day before finals. She doesn't respond for 2 days so I deleted her number. She responds the next day "Hey I just realized I didn't respond. I'm the worst when it comes to that. Unfortunately I don't really have time the rest of the semester. I'm so so busy. Sorry! Maybe next semester."

I think a "who's this?" response would suffice correct? Or just not respond at all. If she was interested she'd make time or would have said something about getting together over the course of the break in between semesters.