I'm thinking it was a few weeks of a budding friendship and 19+ years of stalking. You can't just let him get away like that. You need to hunt him down and make him notice your texts!!

This friend may have become accustomed to you iniating the conversations. They may have a lot going happening on their side as well. If you feel like this long of a friendship is not being reciprocated, maybe it would be worth saying something before giving up.

When someone did this to me I just accept that they didn't want me in their life anymore. Maybe your friend is thinking something like that

I’ve lost a few friendships because I realized it was me carrying them. We all go through it. I’m sorry OP.

It took this long to figure out where you stand?

I’ve gone a year without talking to my friend from high school

I'd be pretty weirded out by someone who texted me every day. That kind of person would be too high-maintenance to maintain a relationship with.