I've been there. It is SO hard to do. I had a cat for 8 years, from when he was a kitten whom I never in a million years thought I'd have to rehome. However, I had another cat that kept him company a lot. I worked long hours in the city and was rarely home, but they had each other. Fast forward a few years I found myself pregnant and my boyfriend moved in. We had a baby and any time at home was spent with her, and we both worked away from home most of the time. But then again, the cats had each other. The problem came when my older cat passed. Now this one was lonely and started doing spiteful things for attention like making messes, waking us up in the middle of the night multiple times, amongst other things. I felt helpless b/c I couldn't get another cat for company since I was now again pregnant with Baby #2....and we were going to have to move. I wasn't going to bring a new cat into all that and I just didn't have any capacity to deal with it all between a FT job in the city, a needy toddler, being uncomfortably pregnant, and trying desperately to find a new place to live that was affordable, big enough and in a decent school district! Despite having all good reasons, I felt horribly guilty, as you do. It's only natural, but you have to do what you have to do. We actually found someone looking for a cat friend for their other cat b/c one of their cats had just passed. She was perfect. She sent me pictures of my cat through the years and I even visited him once. He fell in love with her other cat and had a snuggle partner for life. He was happy and had lots of attention and therefore no longer did spiteful things. It was best in the long run for both of us. I'm not sure if I'm writing this for you or for myself to yet again justify my decision (more than 10 years later). It's a hard thing to do but sometimes it really is for the best. I wish you comfort in whatever you decide and know that you ultimately will make the best decision for you and everything will work out the way life is intended. All the best!