Sadly these things happen all the time, and we never expect them to happen to anybody close to us. Please do not feel bad that it had been so long since you had spent time with him. Instead let it show you the importance of spending the time with the ones that you love from here forward. Let him be at peace, and may peace be with you and the rest of your family during this difficult time. Many condolences for you brother.
Take a beat and smoke a good one with his memory.