Is a cheating husband still a Catholic?
Like any family, the Catholic Church is composed of people who make mistakes, both great and small; however, a person remains part of the family of the Catholic Church unless he/she leaves by a formal act such as joining another denomination or religion. This applies to a spouse who is committing adultery. The teaching of the Church on adultery is that it is a sin, which when confessed, is forgiven. The action on the part of the offended spouse, as hard as it may be, is reconciliation.
When a neighbor's husband is cheating sometimes it is better to let her find out on her own. It is common when a friend tells a woman her husband is cheating that she will verbally attack the friend rather than to believe her husband is cheating. She also may well be suspicious of her husband cheating on her and it is their private war.