Am I in the wrong here?

Well, basically, at the weekend, my family and I went down to visit my nan and auntie. Now, 90% of this time was spent talking to these people, and I was very social around them. However, my boyfriend is going through a very tough time at the moment, so for a little bit of a day was spent just calling him to cheer him up as he's had a shock in his family life. Now, when we got home, my mother went CRAZY at me, started calling me selfish and inconsiderate to other people's feelings because I spent this small time talking to my boyfriend, and she said if this happens again, I will have my phone taken off me, and I won't get it back. I feel this is totally unfair, as it literally was hardly anything compared to the time spent with my family, but my boyfriend needed me, but my mum doesn't know anything about what's happening with him. Am I in the wrong here? Thanks :) x