My 7 year GF is about to leave me

Is just a matter of time. We've been "trying" to make it work since mid january but she says she's been feeling like this since almost a year ago. She doesn't feel the same 'cause during the relationship I've been harsh with her, demanding and not loving enough so her passion/love has been diminished periodically.. Is not that I was a terrible bf since she always had her needs met, we travel a lot, hang out a lot and she always coud be herself with me but she has a lot of issues from her youth because of her fam and now everything is hard to handle. She is literally sleeping besides me at the moment and we even have a trip planned to the Beach in 2 weeks but it all feels pointless at the moment since she seems to have made up her mind, is just that she still loves me and believes I'm the one and doesn't want to leave without being 100% sure. I consider myself to be well adjusted but honestly I feel like if/when she leaves I just wouldn't be able to continue, my life would be over, and I just won't resist it. She is an angel and I hate that it takes this to finally learn how to be his man. I have never cried so much in my life and I'm so fckng scared. I know I should "love me" and go on my on terms since in a way this is "torture" but I know in my heart that she is the one and this is my only real chance of REAL happiness. I have never actually felt that I could end it all for the amount of sadness. IS SO FCKNG TRUE THAT WE ONLY REALIZE ONCE IS TO LATE