The Lord doesn't want you to feel guilty, It was his time to go home our eternity home in heaven. The Devil is the one who wants us to feel guilty. Please trust in the Lord and surrender all of this to him. Proverbs 3:5-6 Trust in the Lord with all your heart and lean not on your own understanding, in all your ways acknowledge him and he shall direct your path. Also ask the Lord to take your thoughts captive in the obedience of Christ. God bless you! I don't believe your brother would want you to beat yourself up. Enjoy your memories for now and live your life with your eyes on the Lord and just remember Heaven is a much better place than here when you are enduring suffering.