Meaning of "Follow her, spy on her, confront her? Aha, see!"?

Hello everyone. I am reading a novel, and I came across this expression. Could you please let me know its meaning?

After the movie I’d already resolved to head uptown, perhaps even walk past her home, especially now that I knew which side her windows faced. Walk uptown to replay and relive the scene uptown. Or was this all an excuse to stalk her building, her street, her world? Was I really the type who stalks buildings, windows, people? Follow her, spy on her, confront her? Aha, see! Or better yet, bump into her. Fancy running into you at this time of the night!

- André Aciman, Eight White Nights, Fifth Night

This is a novel published in the United States of America in 2010. This novel is narrated by the nameless male protagonist who meets Clara at a Christmas party in Manhattan. The protagonist is trying to walk around Clara's neighborhood in the hope of running into her.

In this part, I wonder what the underlined expressions mean.

I first thought "follow her..." is connected to "who stalks buildings", but then there is no "s" in the verb "follow/spy/confront", so I wonder how that sentence can be connected to the previous sentence, or if it stands alone, what that means.

And I also thought that "Aha, see!" is what he would say to Clara when he really bumps into her, just like he is likely to say "Fancy running into you at this time of the night!", but I am not sure what that means.

Thank you very much for your help.