Hi,
I am very sorry you had to give Sebastian up but.......you did what you knew was best, and that is always the most important thing. I gave up one of my dogs a couple months ago. I'd had Yoshi for two years, but it wasn't working out for various reasons. I finally let him go, and I cried so much, but over time it got better. It was done for the right reasons, and he is happier now. You'll always think about him, but the hurt will become much less, and you have many happy days ahead of you. Is getting another dog a possiblility in you future? Keep your chin up and give yourself a pat on the back for making the right choice.
