idk anymore

There's this girl that i used to like, we dated for a a while and i was really happy with her, we had many things in common and she was also really nice to me. But her sister disapproved of us because we were both girls, we had no choice but to break up and remain as friends, but a day later i found out that she was already dating someone else. How did she move on so fast? The guy she was dating was the same one she told me not to worry about because she only sees him as a friend. I was confused, she made feel special, she told me her secrets, she gave me gifts and i did the same to her but she moved on in just one day? When I asked her about it she said that she dated him because she felt bad for him when he confessed to her and he had good intentions that's why she gave him a chance, but what about me? Was I not worth fighting for? I feel really pathetic because it has been a month since that happened yet i still can't move on from her.