Is the Habashi group considered infidel like the rest of the groups outside the religion, and how should one deal with its followers, especially if they are family members?

The way to deal with innovators (ahl al-bid'ah) is the way of Ahl al-Sunnah (definition): Whoever among them is a caller to his innovation and his influence is feared, he must be boycotted, and people must be warned against him. As for the common folk among them, they should be treated gently, advised, and have the truth explained to them. This ruling applies to family members and others, but a parent must be treated with kindness, while offering them advice gently and with leniency.