Was I wrong?

My boyfriend is going to college and he’s in his 4th year. Well he had to do a big project with another student where he would have to meet up after class to complete and he was assigned a girl. I got pissed and he showed me proof that he didn’t choose his partner. Anyway, I ended up going through his book bag while he was asleep and finding his syllabus that listed the professors email and I emailed her from his school email that’s signed in through his cell phone and asked her if she could change his partner, but pretended like it was coming from him. I didn’t tell him I did this because I was hoping she would do it automatically. Apparently my email caused him to almost fail the class/get kicked out but he explained to the professor that he didn’t send the email. I just didn’t want him to be spending all this time with another girl, I had good intentions. He said he wants to breakup with me because my insecurities are unhealthy and impacting his future and mental health. Was I wrong?