Help I am crying over this girl

Ok so I've known this girl for a while now we work at the same job I've had a crush on her since i met her but when I met her she had a boy friend .I really liked this girl .Then came another girl who is her best friend started working there who I had a crush on too and she liked me and was single. so I was starting to talk to her I got her number but never knew what to talk to her about. Then the first girl broke up with her boyfriend and was single. Then one day at work this dude asked me who I was taking to prom and I said idk. And the first girl was at the table and said she would go with me and I was like ok cuz I was too nervous to ask anyone. Then a couple days later both the girls drove to my neighbors house to pick something up and they saw me and the second girl yelled "are you gonna take me to prom" and I got nervous because I wanted to take her but I already told the first girl I would take her so I gave this idc look. I feel like I hurt her feelings but didn't think of it then. Then this dude at work told me the first girl was looking for a date to ringdance so i was like I guess I'll ask her cuz I'm going to prom with her. So I asked her to take me and she said yes. The second girl seemed to not wanna talk to me and took another dude who she now dates. So after the dance happened I worked with the first girl at work and it felt like we got a little closer but the the thing is I never texted her because she was always with her friends and I always felt like she didn't wanna talk. And I'm getting mixed signals that she likes me and that she doesn't like me( one time she texted me wyd and I was so excited that she must actually like me to text me first but then after she just wanted me to take her shift) and she also was laying her head on my shoulder at the dance. Now she's talking to someone else and is always tweeting "I'm so happy now" and "date someone who treats u with respect"Now I wish just texted her and was more affectionate. I also feel like I let the second girl go just for her and I just threw it all down the drain. Now I'm really depressed about it now because I haven't talked to any girls all through high school and This is the first time I felt like a girl I liked liked me back .i need help with how I should handle this situation because I can't stop thinking about this girl.