Maddy, do you have a boyfriend that gets so angry that you want to take defense training and incapacitate him by squeezing his ball?
I'm pretty sure that hitting a guy in the groin area will at least temporarily incapacitate him--it's very painful.
If you are worried about hurting a man that you are with that might hurt you...get tyhe EFFff OUT!!! Actually kicking a man there can actually incearse his adrenaline an make him more powerful...you go for the eyes he cant hurt you if he cant see you..use a car key, a pen, your fingers anything you can get a hold of.
Maddy, your title says "Angry Boyfriend" but your words are discussing being in a situation with a random nutter.
I have four years of self-defense training and Muay Thai and I would never grab a guy's balls. If you're that close, and he is physically threatening you, you want to slam a knee into his groin. If you make contact, he will be incapacitated. Don't worry about making him angrier - If he's angry enough to assault you in the first place, you do whatever you can and then run.
The title of your post is "Angry boyfriend" - I'm concerned about this, are you worried about your boyfriend attacking you?
No sane person wants to hurt another person, but your own safety comes first.
From your writing you at this time do not have the mental-emotional make0uo to get into a physical confrontation.