My partner (29f) cried and told me (27m) that I have been "terrorizing" her

Hey everyone. Long time lurker, first time poster. I am an American grad student, and it's good to be here.

I (27m) am in love with a girl named Angela (29f) (we all just call her “Angie” though). Angie and I have known each other since she was my upperclassman in college. We’re a somewhat unconventional couple. We both openly love one another in the romantic sense, and she is so cute and sexy. We’re committed to each other for life. However, we don’t want to marry each other, and we’ve always preferred to live in separate apartments, because we both value our privacy.

I and my male friends have a funny habit of sneaking up behind Angie and grabbing her abs. Every single time we do this, she screams and reacts with the most overdramatic, overblown kind of terror. I and the guys just touch her as a funny horny joke, and we always laugh at how unreasonably scared she gets.
Last weekend, Angela and I were out to explore a natural area/park near our city. We live in a very hot and humid state, so for the day, Angie chose to wear short shorts and a very low-cut, spaghetti strap sports bra that left nothing to the imagination. She didn’t even bring a spare shirt. We had a great time in the park, and I really enjoyed the view of my cute, shirtless partner. While we were in a secluded part of the park (there were no other visitors/tourists around), I pulled my classic prank on her again: while we were in a secluded area of the park (there were no other visitors/guests around us), I snuck up quietly behind her and put my hands on her abs. She just started screaming and yelling “oh god, oh god, oh god”, and I had to quickly shush her and tell her that she was dangerously close to attracting attention.

When we came back to my apartment, I decided to pull my prank on Angela again. Angie was sweating so badly due to how hot it was, so I snuck up quietly behind her while she was facing away from me, and I grabbed her bare abs and wiped her sweat off of them with my towel. She screamed so loudly and when I released her, she actually felt down on her knees and started crying uncontrollably and hyperventilating. She was clutching her chest and acting as if I was trying to kill her. I got down on the floor with her and just hugged her until she stopped crying. Then I gave her a ride back to her apartment.

Angela messaged me the day after this incident, telling me that she wanted me to see me. So I went back to her apartment, and the reason she wanted to see me was so that she could yell at me. We got into a huge fight, and she was crying the entire time and told me that I don’t “give a ****” about her and what I’ve been doing this entire time was “terrorizing” her. She was still wearing nothing but the same shorts and sports bra as the day before, and she told me that she was too afraid to put on a shirt or take a shower or do anything at all except stand still and stay awake (she didn’t get any sleep at all) because she was terrified that someone was going to break into her apartment and kill her. Right before I left, I picked up one of her shirts and threw it at her and told her to put it on. Rather than putting the shirt on, she just screamed and flinched and cried harder.

I don’t know what the heck has gotten into Angela. Literally the only thing I did was grab her abs twice, and she just became hysterical. Is this going to be one of those things that haunts us? How do I get over my anger at being accused of “terrorizing” the love of my life? Angela is a commissioned officer in the USAF Reserves, and she's also an expert in martial arts. Her recent behavior is so at odds with how tough she normally is, and now I question her mental stability and her fitness for being in the military. Any general advice on how we can get over this as a couple is greatly appreciated.

TL;DR my girlfriend (29f) has had an emotional breakdown and accused me of “terrorizing” her, all over some silly prank that I pulled on her. I need to know how we, as a couple, can move on from this together.

I and my male friends have a funny habit of sneaking up behind Angie and grabbing her abs. Every single time we do this, she screams and reacts with the most overdramatic, overblown kind of terror. I and the guys just touch her as a funny horny joke, and we always laugh at how unreasonably scared she gets.

We had a great time in the park, and I really enjoyed the view of my cute, shirtless partner. While we were in a secluded part of the park (there were no other visitors/tourists around), I pulled my classic prank on her again: while we were in a secluded area of the park (there were no other visitors/guests around us), I snuck up quietly behind her and put my hands on her abs. She just started screaming and yelling “oh god, oh god, oh god”, and I had to quickly shush her and tell her that she was dangerously close to attracting attention.