I find that writing things out, either in a diary or online on a blog can help me vent some frustration (through the effort in writing) and also help to create a process where I have an outlet this frustration. When writing, I am also able to analyse and understand my feelings, which can help me to come to terms with the turn of events. When all is done an well, I just find that I have a chapter in my story to tell to my future grandkids.
Thanks for letting us all know that you're lesbian, but I believe that getting over heartache is a universal and classic activity that everyone is likely to go through regardless of gender identity. It's important to go through the five stages of grief to get it out of your system. First get yourself in denial that you both have broken up. Then, get all angry that it's over. Bargain with yourself that if you get the love back you will do things differently with her. Sink into depression for a little while and just sulk. Soon enough you'll accept that this happened and move on with your life.
Going through a breakup is hard on a person in many ways. To give yourself the best chance at overcoming the hurt, you’ll need to focus your attention on taking care of yourself and moving on. Start off by making a decision to engage with new people, places and things. Sign up for an art class or join a discussion group to learn new skills and meet new people. You should also make sure your body is getting the rest and exercise it needs to deal with the additional stress of the breakup, so consider signing up for a yoga class or joining a gym.