For me it's depended on the breakup and the severity and circumstances of it.
It never worked for me to start seeing someone else or get attention from others, which just made me feel more sad and alone realising it wasn't the person I really wanted.
I think various thing helped me...
focussing on my DC
posting on mumsnet
talking to friends
crying and getting it out
really spending time with people that loved me
doing new and fun things
nurturing myself with little things like bubble baths
spring cleaning the house and chucking old clothes
new haircut and making the best of myself
Just generally allowing myself to feel sad and bad, but then reminding myself that if things are meant for you they don't go by you. Or that the real "love of my life" was never going to be the one that had me crying.
That all said, my most painful breakup I couldn't really do any of that and instead just slumped into a depression because even with the best intentions sometimes life knocks us down.
Sorry you are in pain, I know how much it hurt when something that makes you happy goes away, and I also just broke up about three weeks ago from a 5 month relationship from a man I was deeply in love with and happy with because he was "shopping around" on dating websites. It was very hard, hurt me very much and I am still moping somewhat.
That said I am making as many plans as I can to see friends and go to new places and trying to fill up life with happy experiences.
I often sneak into DCs bed for a wee cuddle when he's sleeping and smell his hair and remind myself that I am very loved by the people that matter and my destiny will not and cannot ever be tied to anyone who would lie to me, leave me, not appreciate me or fail to give to me what I deserve.
I keep the faith life doesn't work like that and hope you can too
xx