My wife and I have been separated for 4 years due to a bad relationship. Now that she is sick, can I refuse to talk to her?

No! If the relationship is not good, you can get divorced. It's two different things than you evading responsibility now! Responsibilities and Morals: As a husband, you have obligations and responsibilities that you must fulfill. I'm divorced and you can still understand if you don't care. It's really strange, why do you have such a problem? If you are a friend, you should take care of her when you are sick. If you are able, let alone your wife who is still married to you. Don't be too kind or unethical. Since there is no love, why should we maintain this marriage? Harm others and yourself.