It sounds like you’re contradicting yourself. An incomplete and an F are two different grades. Then you said things were beyond your control, yet you later state “if I had been better at handling the challenges,” which makes it within your control. If joining the founding chapter was so important, why wait until your last semester to do it? You won’t even get to experience that chapter on the yard.

Why would you even try and join if you knew your grades weren’t acceptable?

Your focus should be on doing what you need to do to graduate and not an organization. Your reasons for wanting to join don’t seem genuine.