How do I stop the urge of texting him?

Nerds sometimes have difficulty with social cues, so you should make your feelings clear. That being said, give him space, too. You'll want to be direct without appearing clingy. Also,...

You need to respect his decision, regardless of how you feel. Accept your friend status and be patient. Perhaps his feelings will change over time.

The next time they use the nickname, just correct them by reminding them what your actual name is.

Block his number and if he keeps harassing you, get law enforcement agencies involved. Don't stick around and wait for help.

Tell him to stop immediately. If he doesn't, call the police and seek a restraining order.

If you feel suspicious about your partner, get access to their cellphone and look at every activity on their phone.

If his texts are sort of dismissive or he isn't really making an effort to connect, that's usually a bad sign. It's also a red flag if he leaves you...

You could start training him now by getting him accustomed to having weight on his back, basically turning him into a pack-steer. But, he won't be ready to actually ride...