I and my girlfriend already 1year 3month.We already break up for twice,I did something wrong but atlast she decided to forgive me.But this time,we break up for no reason.she told me that she don't know what is love and can't love me.she say she is tired and want to be alone.she don't like people to control her,for me,I just don't want her to do bad thing.I am a easy jealous person,once she talk to guys or guys talk to her,I will jealous and angry.but I never told her,I know if I say out,there will be more quarrels happen.but now,she don't want me anymore,I promise her I will changed and cherish her more.she just remain the same decision and me to hate her for leaving me.I can't go on my life without her.few times,I try to suicide,but I scare.I don't dare to die,I think I am useless guy.I can't protect her and give her happy relationship.I just want her give me last chance and let me prove to her that I love her.I know love can't be forced.but I just want her.I cry for 1week and don't eat for few days,what can I do?

You can work on your jealousy and anger issues and the next relationship you're in you won't repeat this mistake.
Leave her alone and work on yourself

I really cannot live without her!I need her to be with me to guide me,I have no direction now.I think she not giving me any chance anymore.she are happy now and enyoy with her frienda,but I can't.she already forget me and our memories?why girls can change so fast?what can I do except letting her or giving up her?

Like I said earlier, you can work on your issues that were causing the break ups.
It's not that she changed so fast, but maybe she got tired of your jealousy and probably possessiveness.
Work on yourself so you can be emotionally ready for a relationship. Right now you are not.

I know I can't.and I decided to leave.just wish her happy and forget me.

I wish you well.