Sharing Our Innermost Thoughts

Was dating this girl for about 2 years.
She was my bestfriend since 4 years. She was my world, my everything. She was my rock. She supported me through my lowest points in life. And for the while the relationship actually lasted, she loved me the way nobody ever did. We had the perfect relationship until 6 months ago things started getting toxic. She started getting distant from me. I tried everything to hold things together. Nothing worked in the end. We broke up in late October and in early November, I got to know that she was having a fling with another guy. It had been less than 2 weeks since our breakup. When I confronted her, she said that although she still loves me as a friend, she no longer loves me in a romantic manner. That thing shattered me to the core. She asked me if I could stay in her life as a friend. I cut her off for a week cause I didn’t think I could do it. Eventually, I came back cause I couldn’t cut her off . When we were dating, we had promised each other that it doesn’t matter if things work out or not. We’ll stay friends, and so I stayed. As hard as it was for me, I tried to hold myself together. I didn’t take any help from anybody cause even though I have some friends in my college, I don’t trust them enough to open up emotionally. Over the course of November, I made my peace with whatever had happened. A few days ago she went to Delhi to attend a cousin’s marriage. She had told me all about it so I knew. On the night of the engagement, she texted me how badly she misses me and that she thinks that somewhere in her heart she still loves me. This evening, she called and told me all that happened and out of nowhere, she told me that she kissed some random guy she met at the wedding cause they had a “moment”. It didn’t hurt me as much this time. However, I haven’t been able to get that thing out of my mind. How can a person say something one day and do the exact opposite the next day ?
All it did was make me realise how little those words meant to her now. She wasn’t this person. I don’t recognise who she has become now. I let her have a piece of my mind. We haven’t talked since. I don’t have any other friends that I can emotionally open up in front of. I don’t know what to do. Since the last 1 month I haven’t felt my emotions, I’m unable to cry, I feel numb inside. I don’t know what to do.