In pain

I met my beautilful girlfriend at work, I have been single for 13 years so I could raise my 2 girls, they are older now so I wanted to find someone. I loved everything about my gf, beautiful, inteligent, her speacial smile just for me, she called me babe or love. She has 3 kids, was in an abusive marriage, last 3 boyfriends cheated on her, I told her I loved her with all my heart and would never hurt her or cheat on her. I would pick her and her baby up in morning, drop baby at babysitter and drive us to work, pick up her other daughter from school. I made her breakfast and brought it for her, took her to dentist, purchased her medicine and food she could eat, took her to nicest restaurants, drinks, let her use my Yukon everyday, she was sick I made her soup and took it to her. She never received Christmas gifts so I spent alot on her gifts and kids too,Birthday gifts as well, her dad passed away several yrs ago so I got an expensive picture frame with his name engraved, she’s never had a dozen roses, I got her two for Valentines day. I always opened the door for her, totaly and completly in love with her and showed it in every way I could. She started becoming distant and wouldnt talk when I was with her, driving she’d just look out the window or text on her phone, started to hurt. She tells me she needs to focus on her kids and limit her time with me, she went back to work at her old job, stopped texting and calling me, stopped allowing me to pick her up, took hours for her to respond to my text messages if at all, she then said she needed her space, it broke my heart everyway possible, now she wont respond to me at all, I feel I have lost her, was going to ask her to marry me, and move her and her kids into my 4 bedroom home, I dont know what I did wrong, maybe I did too much, maybe I was out of her comfort zone, did she meet someone new at her new job? was she using me? Im trying the no contact rule but im afraid she is going to forget me, I never see her and im dying inside, lost 30 lbs in just under 3 weeks, I run 15 to 20 miles a day to be alone, ashamed to say even cry, its at night so no one see’s, i hurt so much theres no relief, I waited to meet someone like her for so long, in fact 33 yrs 2 months 24 days 17 hrs and 5 min, I remember the day I started looking for her, it only lasted 140 days, the search for her has kept me going all my life, gave me a purpose, held me together, helped during the darkest times in my life, now I lost her, have no purpose, no will, im dead inside, how can a man live with no purpose in life? Along with her went my life, my total will to live, ive thought about walking into the desert and just keep going until I droped. Im lost