There is no “fast” way to get over a break-up, but there are definitely things you can do, to lessen the pain, and get over it quicker than you would if you allow yourself to become to enmeshed in you “feelings of sadness and desperation.”
Give yourself a week to cry and cry and cry and rant and feel sorry for yourself. Then stop. I mean literally stop. Get up, take a shower, put on makeup if you normally wear it, go out and do stuff with other people. Tell your friends and family that you are done feeling shitty, and that you hope they will help you out with this. Part of this means you telling them not to tell you how “sorry they are” or “how shitty the dude is” because you already know that.
What you need now, from your friends and family are distractions, and fun activities, that don’t involve lovey dovey stuff, or couples doing romantic stuff together.
Do not watch any sappy romantic movies, do not listen to any sad music (after this one week of allowing yourself to wallow in pain). Just don’t do it. Instead, watch lots of funny movies and TV shows (I just watched the current episodes of both Roseanne and Will and Grace, and practically shot milk out of my nose from laughing so hard). Find what you think is funny and watch it.
Also, don’t let yourself sit there and wallow (after your week of wallowing). Get up, go out, meet up with friends and do something fun, even if it’s just playing a game of scrabble, or going rollerblading, or going to a thrift store, or whatever it is that you enjoy. But try to not choose something that’s expensive, or you will regret it later. Just do stuff. Fun stuff. Make sure you are busy, and booked, for the next few weeks and months.
You will have moments where you want to break down and cry. Tell yourself to knock it off, and get back on your having fun with people who like you schedule. Be busy, all the time.
Do nice things for other people. That way you can think about them, instead of yourself.
Even though your friends and family will want to tell you how crappy your ex-boyfriend is, tell them you already know that, and you don’t want to hear about him. Tell them that you want to have joy and fun in your life and that you already wallowed about this dude for a week, and you’re now done.
Like @Zenvelo said, cut off all contact with him. Resist the urge to call him, or write to him, or text him, or stalk him on FB, or ask other people about him. Just don’t do it. Do something else. Organize your closet, organize your photographs, look into that art class, or acting workshop you were interested in. Plan your next vacation. Look at some restaurant reviews and decide to go to a neat restaurant that you’ve never tried with your friends, in the near future. Be busy. Don’t sit still.
Don’t allow yourself to think of “what ifs.” There are no such things as what ifs, there are only, what nows. Now I’m going to do this, and this, and this, and all of those things are going to be useful or interesting or fun to me.
Some people say that journaling helps. I’m not a fan of journaling because it makes you think about and relive the pain of the shitty relationship that just tanked. If you are going to journal, write about the things that you want to do, the places you want to go, the things that are fun. But do not write about how sad you are, or try to analyze what went wrong, because most of the time, nothing actually went wrong (except for the fact that this dude was not a good match for you). Sometimes there is no explanation for why one person feels one way, and another person feels a different way. Sometimes people say stuff and make promises, because it’s easier than telling the truth. Sometimes the truth makes people look shitty and foolish.
Chalk up your ex-dude’s “promises” to him not wanting to tell you how he really felt, because either he didn’t know, or his mind changed, or he was just feeding you a line, to get something from you (young guys, and older guys do that all the time, because women, not all women, people, so don’t start yelling at me, fall for that crap, because women are brought up, still in this day and age, to go along with what men and boys want, and not to make waves, or ask for what they need, even if it’s not in their own best interest).
But mostly keep busy. Be busy all the time. If you can’t sleep, then get up and do something else. Just be busy, and do things that are enjoyable to you.
If this dude comes back and tries to contact you, or make you go through round two with him, don’t even talk to him, don’t get involved in any way with him. Don’t fall for the crappy line, “Can’t we be friends?” NO! He doesn’t want to be your friend, and you can’t be his friend, because you already crossed way over that line. Put him out of your life.
Do for yourself now. Be a strong woman who is capable of going to a restaurant by herself, and ordering whatever the heck she wants, without having to pretend not to be hungry, or without having to worry about ordering onion rings and garlic bread and hummus in the same meal and having bad breath, or looking like a glutton in front of some dude. Do what you want, go where you want, onward and upward, past this little bump in the road, this little glitch in your computer program.
Enjoy yourself, and anticipate the day when you will be able to say to yourself, “What the hell did I see in that asshole?”