welcome to COL Forum!
We are of course obliged to show charity and patience to all fellow men and particularly to those who are severely misguided about such serious issues. No one, however, is obliged to imperil their faith if they do not feel ready to debate complex theological issues. Otherwise only saintly theologians could be disciples of Christ. Be very careful in dealing with Jehovah's Witnesses who are often intensely - but very selectively - trained on chosen passages of their own version of the bible in ways aimed at spreading confusion among Catholics about their faith. There are books and specialists who can illustrate to you how they study for years how to use the Bible depending on the creed of those they want to target.
So I would not debate them without a sufficient preparation on your behalf. When they cite or quote alleged passages of the Bible, always demand that they give you the exact chapter and verse and then compare what they said with what the actual
Bible says, in a version that is approved by the Catholic Church. Know that their bibles are severely edited and contain gross mistransaltions of the original text. Once you have done that - which in most cases is enough to see their errors, take the time to research the teaching of the Church - meaning: Papal Magisterium, the Councils, the Fathers, the Catechism and so forth, not just any theologian who may or may not be in sync with what the Church believes.
Know also that they do not even qualify as Christians, for to be a Christian one has to believe at least in the Unity and Trinity of God and in the Incarnation, death and resurrection of Jesus Christ, true Man and true God, the Second Person of the above mentioned Most Holy Trinity. They do not believe that Jesus is God and they reject the Trinitarian faith, so they are not Christians.
St. Paul says (1 Cor 12) that no one can say, “Jesus is Lord,” except by the Holy Spirit
. So how can they be inspired by the Holy Spirit when they deny the basic tenets of Christianity? Besides, while it is true that the Holy Spirit cannot be controlled by any man or group, it is certain the the Holy spirit ordinarily and without error speaks only through the Catholic Church, since Jesus himself promised as much to Peter and the Apostles. Of course fragments of truth can be found in many different denominations and even other religions, but the truth can be found only in the Catholic Church, otherwise Jesus would have lied to us and we would not have a reliable source for our faith.
Of course your friends are good people and probably many of them do lead exemplary moral lives. I know quite a few JWs myself and many of them indeed are good people. But being a good person is not enough to turn us into prophets and apostles, and much less does that fact alone protect us from error. Otherwise we would not need a Church, and we would be saying that any man can be infallible, always and without exception which is impossible: many good people say contrary things and disagree with each other. They cannot possibly be all correct at the same time. OTOH saying that somebody is wrong about something is not the same as saying that he or she is a bad person.
My humble suggestion is that you take the time to read what the Catechism - or at least its Compendium
says about a certain issue that might appear difficult the way it is presented by the JW (or any non-Catholic): http://www.vatican.va/archive/ccc/index.htm
for the bible see our Scripture & Ancient Writings Library viewforum.php?f=225
for common objections to the Catholic Faith see:FAQ's-Explaining Catholicism: Why do Catholics believe in..?viewtopic.php?f=223&t=21232
in the first entry of that thread, scroll down to where it says "Non Christian", you will find links to the following contents:Are They Awake on the Watchtower?
Distinctive Beliefs of the Jehovah's Witnesses
The God of the Jehovah's Witnesses
History of the Jehovah's Witnesesses
Strategies of Jehovah's Witness
Stumpers for Jehovah's Witnesses
More Stumpers for the Jehovah's Witnesses
FabrizioParty like it's 1773
No one can be at the same time a good Catholic and a true socialist (Pius XI)