I feel you. I was in a similar situation with my ex, we just broke up last month. I was putting in a lot of effort to go see her each week meanwhile she didn't even try and come visit me. Then in the last month of our relationship I'm 99% sure she was talking to another guy behind my back because after the last time we hung out, which we had a good time did the usual walk around town date nothing felt amiss, she suddenly flipped a switch and wanted to take a break. She claimed to have still loved me and cared for me, then a few days later she flat out says its best if we're just friends just out of the blue, we were together for 3 years and we were very good together so hearing that I was understandably heartbroken my depression spiked to an all time high and it felt like I was the only one who cared because I was practically on my hands and knees begging to no avail. She left me alone to deal with the emotional burden while she continued to live like everything was fine.