After a dramatic turn in events, do I still have a chance?

Basically, this girl ive known forever and I got involved after she broke up with her boyfriend. Before they broke up she told me shes had feelings for me the entire time shes known me (10 years). We have hooked up in the past and I also did kinda hurt her about 6 years ago. But she started dating a friend of mine about 5 years ago. So after they broke up she came to me again and said shes had a thing for me the entire time she was with him. So we started hanging out. We did relationship-esque things like dates, getting physical and all that. it was great, she kept telling me how happy she was. Of course we had to keep it secret because the guy she dumped was in our group of friends. I realize now that we may have rushed this, but it felt good at the time.

After about 2 months of this he came to her house one night and told her that he cheated on her for the entire 5 years they dated, and it was with guys not girls. She was shocked and crushed. She told me she didnt have the emotional stability to handle our relationshi and that she might be distant for awhile. I told her I understood. We still hung out in the same context though. One night we were even hooking up and she left in the middle saying "I cant be doing this right now."

Then i asked her out to dinner and she said "i cant be going on dates right now it will mess everything up. I need some time to figure myself out." I told her that i understood but my feelings for her didnt change. I also told her not to leave what we had in the dust.

Then about 2 weeks later she went on a date with someone. She told me that she needs to "test the waters and see what i really want. Im sorry I have to talk about this with you but in the long run its a good thing. I need to meet new people but I know I dont want a full time relationship."

So now I dont know what to do. I feel like she used me as a lifeboat kinda, like she was scared to be single so she went somewhere she felt comfortable. To be frank I dont want to be around her if shes gonna be with other guys. We are still, at least in theory, friends. And we have the same friends. Part of me says she still might come back around but I know its an awful idea to think like that. Im still not sure if she has feelings for me or not. Conventional wisdom says if she did she wouldnt be dating other people, however its possible she doesnt want to deal with her feelings for me. I think she assumes her and I would have to be a full time relaitonship. But now we talk maybe once every two weeks. I used to get multiple messages from her per day.

So do I:

a) cut her off

b) play through the pain and be her friend.

c) tell her I feel used and that Im not her fallback guy. At this current juncture Im not sure how productive this would be

Thanks for any help anyone can give me.