My girlfriend broke up with me and I've never felt so bad in my entire life

Do any of you guys have some advice to deal with this? Please? I feel stupid for even reaching out to a reddit community but I have no one else to turn to, sadly. I just feel like this is the greatest failure of my entire life. I've had so few successes since I've become an adult and I thought my relationship was one of them, but look where I am today...