I can't deal with this situation....

I just ended up a 4 years relationship. It was quite special for me, we plan our future share life support each other go through so many things,I'm happy and appreciate that have him in my life I thought he is the one we will share whole life. Two weeks ago I wake up at morning I got a break up message from him. The reason is his feelings changed don't want to be with me anymore, I never thinking one day we will end up this relationship. Suddenly I feel lost everything,there is no plan no hope no future. I can't understand his reason I love him with my whole heart feelings are changing all the time, one day happier, another less happier. Relationship based on love is robust against feelings changed Feelings come and go, but love is more than feelings and emotions... Everyday I look back what I have done make it became like this, I was keep the hope this is just happened for now, we will fix it in few weeks then back again But..nope, he leave already. This is really awful, until now I still can't stop checking on him, just wish he also feel the same, missing each other, our past, feel sad. At same time I afraid if he jump to other new relationship too quick, I feel fear every single day.... How I can focus on myself out of current situation....I could not find the meaning of my life There is no passion move on