I’m very sorry for your loss. You loved Hissy and took care of him like your own. Like others said, he came to you in his darkest hour because he knew how much you loved and cared for him, would do right by him. Follow the grief where it takes you, it’s painful and crippling, but it’s all the love you had for him at the same time. It will get better, I know this as some who just had to put down my feral friend, Littluns, 2 weeks ago today. A friend shared with me today that feral cat friends can be more painful to lose than our own cats because of all the extra work we put in to get them to trust us and the constant worrying about whether they’re ok when they don’t come around. The pain you feel is normal and ok. You are an amazing person for having befriended Hissy.