It is hard to let go of someone, especially if they have been in our lives for a long time, but there are red flags that will alert you when to let go even if you love them.
YOU CHANGE - If you have made major changes in your life, such as quitting smoking, quitting alcohol, quitting gambling, etc. You should definitely cut the people out of your life that still do those things. Family members must be kept, so just try to avoid them until you have at least a year away from your vice. It is sometimes a good thing to let someone you love go. Both of you may grow and someday be friends again.
THEY CHANGE - If your friend dives into an addiction, such as cigarettes, alcohol, gambling, pornography, sex, etc., you must cut them off. It will actually help them to hit their bottom. You can always contact their family members and try to help from a distance. Do not get involved in an intervention unless you are a very influential friend.
THEY STEAL - If your friend steals from you, their employer or someone else, it is time to let them go. Even if they have not stolen from you yet, it is just a matter of time. This person is not your friend anyway.
THEY ARE VIOLENT - Violence toward you, someone else or an animal is a very bad sign. If you see violence in a friend, move! Change your phone number and address and do not contact them again. This is not something that can be helped very easily.