Aw man that sucks! Although I wish we could all choose such a peaceful ending surrounded by those we love most, showing such affection, being entirely present knowing and honouring the moment as important, precious and creating a bittersweet snapshot of a life, the kind memories are made of.
Yes. You knew the decision was right and in the absolute best interests of your little buddy, letting go for all the right reasons is one of the single most compassionate things we can ever do, it says that we view the life of another more than the avoidance of the shattering feelings we know we must endure.
In one way it will always feel as though life has lost something, in another, that is only because you had something. If someone could wave a magic wand to take all of those feelings away and remove the memory of Merlin, yeah, you would feel good right now but as you know all too well Brother, you would have sacrificed so, so much more.
I'm not gonna go an as long as usual, you likely are not in the mood for long missives, especially when they are saying things you know in your soul anyway. In many ways, even when you know they are well meaning, words don't help much. Grief is different everytime no matter who or what it is for. It is a very private experience and we must enter one end of the tunnel to emerge at the other side.
You Faith and Cleo will all pass the way you feel right now and cheer will return to life, this doesn't mean it is done, losing a love is never ever done, it simply means that once again in life, you have come to terms with and profoundly understood one of life's cruellest values. Love and pain are inextricably linked. I wish you all the very best and hope that you find many, many reasons to smile and laugh even though the grief is being processed. Take good care of yourselves my friend.
You have photos, memories funny stories and an indelible mark on your heart that says one thing that you will never forget, although Merlin is no longer with you in the same form he was before, your lives have been forever touched...