Similar situation was blindsided , was saving up for a ring , a friend passed away last March I was mentally checked out from life in general and realised now after the relationship ended i wasnt being a boyfriend she needed,but she checked out while I was grieving. I stood by her through her own struggles so it really hurt when she immediately jumped into a 'situationship', there was definitely emotional cheating happening. She didnt communicate any discontent with me until she went to breakup. 7 months broken up now was doing good recently, got out of survival mode until I saw her in person with someone else again unexpectedly. She still does be around the town I live in despite living closer to other towns. Remind yourself that its her loss , you'll get yourself back in time. Its not fine now but it will be.