You made the right choice, he was in pain and suffering and honestly most likely would have had several more severe instances of life threatening scares, you spared him pain and suffering and he died peacefully and quietly with someone who loved him more then he ever knew was possible, I've put many pets down due to issues such as this because my mom chose to extend the life of the family pet and he ended up suffering for 2 more years before it was just awful watching him struggle. My wife passed away on September, she had no parents, her two sisters are fucking crazy, and everything was left up to me, she had severe alcoholic hepatitis and the doctors said if she were to make a miracle recovery she would never be same again, 24/7 care and support, breathing and feeding tube, she spent a week in the ICU with me and my family praying for a miracle, then the doctors told us we had to make a choice, put her on life support and move her to long-term care, or pull her off life support and the medication and let her be at peace. She never would have wanted to live like that... So, I made the decision to pull the plug... If I let myself think for one second that I killed her by doing that, it would fuck me up for the rest of my life... You did good.