Let's face it - life is a bi*ch and things don't always work out as planned. This is exactly why you need people, who always have your back, to get through this tough time. But this works both ways - there are some people who need, and rely, on you, as well. And if you know what it is like to be in the other person's shoes, you also know how to help a friend through a situation you've faced in the past, too. A break-up, for instance, is one such scenario most of us have been through. We know what it's like to love and lose; or feel unloved, even. And in such a situation, it matters how you respond to a friend going through heartbreak. Watching your best friend go through a break-up isn't easy. What your friend needs is a support system that will be her shoulder to cry on, a punching bag, or just a good listener; or, maybe, sometimes, it's all in one. Break-ups do that to you. Your friend needs to know that you're there while they are heal at their your own time and pace.
When it comes to dealing with a heartbroken friend, don't let your judgement cloud your thinking. It's easy to get emotionally-charged and want to hate the person who did this to your friend. But, between your friend and you, you're the voice of reason. The aftermath of a break-up may make them want to do things they wouldn't do normally. Sometimes, these things are really stupid and immature; but you need to remember that moving on is a gradual process and no one really learns unless they make some mistakes.
There is also going to be a lot of listening involved. This might just include listening to the same damn story again, and again; but, that's okay. They need to get it out of their system. Be patient with them when they are going through a messy situation because venting is sometimes the best way to heal. And, all you have to do is be present to help them get through a tough time. Remember, all they need is a shoulder to cry on and a person who'll give them hope that all will be well, eventually! And even if it isn't, they've got you.
Let them make their own mistakes because break-ups tend to bring out the worse in a person. Let them offend you, or do something that you're against. But, be sure to make it abundantly clear if it's against their own healtha and well being. Eventually, you have to understand that she may be your friend; but, she's also her own person. Only she can make the decisions of her own life. You can guide her and help her through it all. And, if she screws up, just be there for her - sometimes, to say 'I told you so' and other times, to help her find a way out of the mess. It's not your struggle, it's theirs. You're only their back-up, there to run in when required, but they are the ones who have to win that war. Be their cheerleader and constantly remind them that they are doing just fine. Of course, you'll have to stop them from hurting another person qand themselves, along the way. But, if their way of healing involves a lot of drinking and partying, then drink and party with them; only till it doesn't become a regular habit and toxic to both of you. Be sure to give them time. It really is the best healer.
It's the rule of life that nothing lasts forever, not even sorrow. It is only a temporary phase. You can always be there for them with these simple effortless ways, and help them get through it. After all, a friend in need is a friend indeed.