I am sure most of us can relate to your situation, or otherwise we wouldn't bet on this board. If she is getting married, let it be. If someone wants you in their life, they will make a space for you. You wont have to beg for it. Know that everything happens for a reason, but we can never see it when we are looking towards the future. We can only connect the dots when looking in the past so it will take time until you see and realize why this has happened to you.
Start surrounding yourself with people. Start doing fun activities with guy friends it will help your mind focus on the activities rather than her. I don't really know what works for you, but actually shedding a tear or two, and letting it all out can help. After all crying is the body's natural way of calming your system down. I know it hurts and I know it sucks, but like a wound it heals over time. It's all about your mentality.
Know this, it's tested and proven, that if something has happened over 3 months ago, it has no affect on your happiness unless you are hypnotizing yourself and making a big deal out of it. An experiment done, was with people getting their legs amputated and lottery winners. After a year, when asked how happy they were, both groups were equally happy. Therefore you are CAPABLE right now in this very moment to feel good and happy.
Would you really want someone who doesn't appreciate your uniqueness and character? Even she comes back to you in this very moment to ease your pain, would that be right? Believe that the Universe is saving you for someone even more special. Or perhaps this woman needs to learn something about herself through a failed marriage you never know.
Anyways it's not your job to know, all you have to do is focus on yourself. Love yourself, cause to want to take your life means you have lost the love for yourself. Be proud of who you are, and yes at this point you can feel a bit of anger towards someone that did not appreciate you and let you get in this state of self destruction. With time you will be able to forgive and move on, but at this very time, it's ok to express anything that you feel and hold it within.
If you are angry be angry, if you are sad and feel like crying, cry, basically anything that will let you get out all of the tense you are feeling. Start with watching funny movies, relaxing movies to shift your energy. Make a list of all of the things you are really grateful right now in life. Make a list of all of the qualities you posses. I know where you are standing right now, and some 7 years ago I was there. Gets better with time and a few years later I saw it's a necessary experience.
I will allow myself to quote something from a movie. "Life is not about how hard you can hit, but about how hard you can GET hit and keep moving forward". So you got hit hard, perhaps the hardest you have ever been hit. You can accept yourself as a victim, and self pity, or you can stand up and keep moving forward.
Know this as well, some of the finest wines in the world are made from this special type of grapes, where they are left completely without water and only the grapes that survive are used. I hope you find the power within yourself to like yourself, to believe in yourself that you can 'stand up' and move forward.
Henry Ford once said, 'Whether you think you can or can't either way you are right'. Keep us posted and hope you feel better.