My so called “friend” has something going on with my ex and I’m shocked

TL;DR

I (female age 16) had a friend who I’ve known for 3 years, I loved so her much because we did everything together, I was even calling her my sister at one point. But when school started we just went our own separate ways and we no longer talk no more but we never had a problem we just started hangout in different crowds but at the time I was still dating my ex until about 3 months ago when he broke up with me, I was so heartbroken. Me and him (same age as me) have been off and on for about two years so I would always tell her how I feel about him and how I still love him but I recently just found out that they have a thing with each other ( a thing is when a person is talking to someone everyday but in a flirty manner) and I’m so upset because I don’t know why she would do this to me and when me and him broke up the first time she would always tell me things like “why do you even like him,” “ he’s not right for you,” “he’s ugly” and so much more and now I’m just shocked because I don’t understand why she would go with him, after everything she told me about him, I don’t know what I did to make her go after him too and when I see her in the halls she’s always being petty when she looks at me. I’m so upset right now because even if we went our own ways I would still never do that to her and I’m trying to move on but I’m just so hurt at the fact that I would invite her to things when I was with my ex and I still have hella feelings for my ex still and I feel so betrayed and I’m trying to get over it because i shouldn’t care who my ex is with but for someone that I used to know so well, go and do this to me is just messed up. I need help can someone give me advice please

Submitted May 25, 2019 at 06:09AM

TL;DRI (female age 16) had a friend who I’ve known for 3 years, I loved so her much because we did everything together, I was even calling her my sister at one point. But when school started we just went our own separate ways and we no longer talk no more but we never had a problem we just started hangout in different crowds but at the time I was still dating my ex until about 3 months ago when he broke up with me, I was so heartbroken. Me and him (same age as me) have been off and on for about two years so I would always tell her how I feel about him and how I still love him but I recently just found out that they have a thing with each other ( a thing is when a person is talking to someone everyday but in a flirty manner) and I’m so upset because I don’t know why she would do this to me and when me and him broke up the first time she would always tell me things like “why do you even like him,” “ he’s not right for you,” “he’s ugly” and so much more and now I’m just shocked because I don’t understand why she would go with him, after everything she told me about him, I don’t know what I did to make her go after him too and when I see her in the halls she’s always being petty when she looks at me. I’m so upset right now because even if we went our own ways I would still never do that to her and I’m trying to move on but I’m just so hurt at the fact that I would invite her to things when I was with my ex and I still have hella feelings for my ex still and I feel so betrayed and I’m trying to get over it because i shouldn’t care who my ex is with but for someone that I used to know so well, go and do this to me is just messed up. I need help can someone give me advice please