How can I get a friend to forgive me for getting upset with her for no real reason?

A few weeks ago, a friend of mine asked me to help her with her English ignment. Since she was my friend, I was more than willing to help. However, when my family found out I was helping her, they started nagging me about the fact that I was okay for her to ask me to help her with her ignments, but because I am from a different culture, she's only interested in friendship. Also, they felt it didn't make sense why she would be asking for my help when she could have easily typed up the ignment herself. But, I told them that she has a very busy schedule with work and school. Afterwards, I was so angry at them for poking their noses in my business and treating me like I was a child. I wanted to tell them off, but they're my family members, so I remained silent. Unfortunately, that anger got the better of me and when I saw my friend again, I spoke very rudely to her for no reason. Now, here I am today and I have sent her flowers & apology e-mails to no avail. What do I do?