Is it normal to be thinking this much of a situation ?

I went out with the boy once. And it was a substantial once. I know he meant things the way i did and I could swear on my life that i felt things i never felt before. First off, i think i am a very mentally ill person and i struggle with a lot of teenage girl things. Im pretty sure I have schizophrenia, depression, horrible self esteem and anxiety. But he did too. Well during our relationship, he confessed about his depression stuff and an ex fiance. After he told me that, i fell hard and couldn't take it easily for some reason. I want engagement and he made me feel like sh*t for the littlest thing. The only thing i think about is her and him. Well i have a lot of other interests but i think this event or series of events has caused me to crumble tremendously. Then I think of him and how to keep him because we've been on and off for a while. I keep feeling like i dont matter as much and how great his past relationship must have been. I feel like if i just became her, i could go back to him and we would be inseparable, engaged, happy. I also started reading astrology and how his and his ex's signs were so compatible and mine wasn't as much. She was Aries, he was Leo and i was cancer. I don't want astrological advice cos i don't believe it. But i find all these reasons that she's more worthy to boys than i am. And how she sits higher than me on a lot of levels. Then i start thinking of him again and how much i care about him and ways of making our relationship better after a month of breaking up. I see that girl all the time and Ive recently dyed my hair, bought a few new clothes and have never felt so low because im modeling after her. I have never felt so low. He has contacted a couple of times but I'm so wrapped up in all these things. Once of my family members is currently dying and its making all this worse. I'm trying to focus on school because I'm trying to keep my ambitions intact, despite all these strong set backs. I need to know why I'm dwelling on this and why it has become such a big deal and how to make it stop and be normal again. Please