If I were a theology professor, or even a religious literary professor, I'd flunk you.
...the word of the Lord came unto me, saying, Before I formed thee in the belly I knew thee; and before thou camest forth out of the womb I sanctified thee, and I ordained thee a prophet unto the nations. Then said I, Ah, Lord God ! behold, I cannot speak: for I am a child. But the Lord said unto me, Say not, I am a child: for thou shalt go to all that I shall send thee, and whatsoever I command thee thou shalt speak. Be not afraid of their faces: for I am with thee to deliver thee, saith the Lord . Then the Lord put forth his hand and touched my mouth. And the Lord said unto me, Behold, I have put my words in thy mouth. See, I have this day set thee over the nations and over the kingdoms, to root out, and to pull down, and to destroy, and to throw down, to build, and to plant. (Jeremiah 1)
You think the people the Lord is threatening are folks just like your neighbors...good, decent and, for the most part, honorable. But unless you see them as the Lord sees them and understands them as He does, your judgment is faulty. These weren't just people who were members of a different church, or different religion, they were people who covenanted with the Lord, then rejected Him to adopt profligate heathan lifestyle, often one associated with the sacrifice of children. (The women who agreed to divide and eat their babies during a time of famine are representative of these types of people. Had they repented when Jeremiah and the other prophets warned them, the Lord would have spared the city.) Instead, they sought these prophets lives. The Lord told the people to ally themselves with Babylon and not Egypt, and this political message was so unpopular that the prophets became enemies of the state. The Lord also called them to repentance, and they rejected that advice as well. Babylon had placed Zedekiah on the throne and he betrayed them. So they were fully ripe for destruction.
The problem with leaving the Jehovah's Witnesses is that you treat the JW God as being the same God of the Old and New Testaments, and this is a fallacy, in my view. Leave them, but don't assume God is representative of the being the JWs preach. He is not.