<human>: To give a little context.. 
Ex and I broke up couple months ago. We dated for about 3 and a half years and ended it on sudden terms (long distance).  After a couple weeks, she found someone else, but was constantly having discrepancies with her new boyfriend.  I've stuck by her side all this time to help her through everything she needs since we've been best friends for even longer than we dated.  It's eating my alive living every day knowing that she feels for someone else when I still feel so strongly for her, but I feel like I can't just turn my back on her and walk away because I'm her main and most reliable support line.. what do I do.. I am at my emotional limit.

Could you distill the essence of the text into 1-3 sentences?
<bot>: Still have feelings for girl I dated for 3.5 yrs. she has new boyfriend. I'm still her best friend. Want to move on but I don't feel like I can turn and walk away from her.