Is This All My Fault? What Can I Do To Make It Right?

No, it's not that your wrong. But you did mess up but you not messed up and you should've told them if you were gonna be der or not. If you wasnt sure you should've told them dont come until you was sure if you would be there. If they're mad at you explain to them the situation n tell them u just messed up that once and next time you'll try to remeber. If they're are not mad you cool, you good, and dont worry bout it. They are your friends so they should forgive you.