I understand your feelings and I love my pets. That said... you must drop the urge for revenge. Nothing good can come of it, and you could end up in serious trouble. You have already intimidated him so that he retreats from you. Let that be enough. If Ruby were alive and could speak, what do you think she would say to you? I'll bet her loving heart would not want you to focus on negatives.

How to drop it? Like a hot coal. Just drop it. It's great that you've gotten fit. However, this incident and your anger are eating away at you and clouding your judgment. You speak of church and I assume you are Christian so I will quote:

Romans 12:19-21 King James Version (KJV)
Dearly beloved, avenge not yourselves, but rather give place unto wrath: for it is written, Vengeance is mine; I will repay, saith the Lord. Therefore if thine enemy hunger, feed him; if he thirst, give him drink: for in so doing thou shalt heap coals of fire on his head.

Matt. 5 Verses 38 to 48
[39] But I say unto you, That ye resist not evil: but whosoever shall smite thee on thy right cheek, turn to him the other also. [40] And if any man will sue thee at the law, and take away thy coat, let him have thy cloke also.

Another non-Biblical quote "Anger is an acid that does more damage to the vessel in which it is stored than to anything on which it is poured."

Recently I've discovered the philosophy of Stoicism and I find it helped me a LOT with my anger. "Stoic" has come to mean someone who is not emotional, but that is not what the original philosophy intended. A Stoic was someone who believed that satisfaction and contentment in life was only to be found in living a virtuous life. Any negative emotions must not be dwelled on but should be processed and let go of. A Roman emperor, Marcus Aurelius, actually forgave a friend of his who turned traitor and tried to break up the empire. As you can imagine this was unusual behaviour for an emperor (!) but he was a Stoic and saw no victory in revenge. Stoics try never to react in anger, but to step back and wait until their head is cool, and then respond in a rational manner.

I will leave you with a quote from Nietzsche: "Beware that, when fighting monsters, you yourself do not become a monster... For when you gaze into the abyss, the abyss also gazes into you."