I accidentally sent a text
How did you send a text by accident.
I wanted to send it to my best friend but not my boyfriend
Although you did not mean to send the text to your boyfriend, i am sure that your boyfriend will understand that you made a mistake. Its fine to make this error every now and then so dont beat yourself up about it.
But what if he breaks up with me.
If your boyfriend truly loves you, he'll understand that the text was just an accident. There is no point in thinking about something that is not in your hands anymore.