Give your sister a genuine shy teddy bear. It's a great gift for girls. You should tell your sister that the breakup is because the two of you are not suitable for each other and that you will meet someone better. Encourage her and comfort her. Show her the way like a beacon.
Her birthday is coming soon. You can also choose a more creative gift for her, such as a customized DIY cake. You can make it together to make her feel happy. It is said that when a person is happy, there is nothing to remember. Even if it is just a temporary forgetfulness, you, as a sister or brother, should make her happy.
Giving handmade chocolates is also a favorite of girls. The chocolates are completely handmade. You can also write blessings on the chocolates. It is very creative. If your sister likes to listen to songs, you can give her a CD of her favorite star, but try to pick some cheerful songs to play for her to make her feel better. Don't forget to wish your dearest sister a happy birthday. Comfort her, encourage her, forget the past, and start over.