Your conscience is really the culprit here, and in fact, I think good heart is almost second to none. I do not see the reason why you should allow the self guilt to over-burden you. Even from your construction of English language, I can perceive you are intelligent and competent. You are advised to practically leave behind the 'generic opportunity' which you were denied,that is, the opportunity to spend four years in school. In which case, you may not have been better! Otherwise, you may try to enroll in degree programmes with QU or other universities in Qatar. You should also write challenging professional qualifications, the ones which the degree-qualified colleagues in your company are eligible to write too. Ultimately, this would bring you at par with them, and there wont be any room for complex anymore.