How they compare
Both are for married and attached people, are free to join, and put privacy first.
Ashley Madison is the best-known affair site, with a large member base. Women use it free; men buy credits to start conversations, from about $49 for 100, which adds up quickly.
Victoria Milan, running since 2010 and based in Malta, lets you anonymize your profile and shows only approximate locations for people near you, plus a travel feature for other cities. It claims a roughly even gender ratio, which we can't check. Messaging needs a paid plan, priced at sign-up.