I need advice on a girl!?

She just got braces a week ago, and I saw her for the first time in months since we broke up. She looks horrible, and behind her back I said, "She looks fu*king ugly with braces." And it ended up that she was right behind me when I said it. I apologized in person a few days later, everything is cool between us but it seems like she is still hiding her feelings. Should I buy her a rose and add a card to it saying something sweet and nice? I don't want our friendship to be awkward because I messed up. If I do get her a rose, what color and when should I give it to her? Like leave it on her doorstep and surprise her? She already forgave me but I feel like it's not enough so that's why I thought maybe a rose or something else to show her that I care about her as a friend