***HOW TO DEAL WITH FAILURE: take a short time to mourn/grieve. Get over it and yourself. It's not a big f-ing deal. You're still alive - it didn't kill you to fail; you have your health, your brains, your livelihood (hopefully). There is always someone in much worse circumstances - not just in sub-Saharan Africa and South Asia, but here at home. If you're reading this, you have access to a truly endless wealth of information. You can and will get better, MUCH MUCH better. Now, step away from your personal emotional attachment. What went wrong? What went RIGHT? Who fucked up? Who did well? What part of it is your fault? What can you fix right away as a person (yourself, maybe with help) and professional (yourself, definitely with help from more senior people)? What will taken her to fix? What lessons do you take away from this?
Be as truthful and transparent and clear-eyed about yourself and your performance and that of others as you can be. Don't delude yourself. Don't project your own issues onto others. Don't assign blame. Don't have any regrets. You (hopefully) did your best. You'll come back stronger and smarter. Learn the lessons, improve, iterate, A-B test as MOVE ON ASAP! Don't linger in your own guilt-and-blame pool. Wipe off the dirt and carry on! Life's too short for self-pity and you have much too much to accomplish still!
Business is business and personal is personal. Don't mix the two. You will be burned.