Well, I'm Catholic. Are you baptised? If not, then in Catholicism that's (more or less) considered a "natural marriage." A natural marriage is valid but not indissoluble (i.e. you're "really married," you're not "living in sin" but it's not a covenantal marriage, therefore doesn't have an unbreakable bond, so divorce and remarriage isn't impossible in the way you are thinking). For a marriage to be indissoluble, it would need to be a sacramental marriage between two baptised people, generally this means in a Church (and, if you're Catholic, it has to be a Catholic church because reasons). Only a "sacramental marriage" is unbreakable.
Even in a sacramental marriage in Catholicism, it's not exactly divorce that's the problem - it's discouraged, but it's also recognised that there are times when divorce is necessary for reasons of the safety or welfare of one or more of the family (e.g. husband is gambling away the family money and wife must sever the legal bond to avoid being unable to feed the kids). It's just that in a sacramental marriage, divorce does not break the sacramental bond. In that case, remarriage would not be possible (however, again, it's not clear you are in what the Catholic Church would consider a sacramental marriage).
Catholicism also has a concept of something called a "decree of nullity" usually known as "an annulment." This means that the Church has investigated a marriage and found that at the time the couple entered into the marriage, something prevented formation of a sacramental bond, i.e. they basically didn't understand, or were not actually choosing freely, a covenantal relationship. The best known example of something that would prevent formation of a sacramental bond would be a coercive situation that prevented one or both parties entering the marriage freely. For example if the bride was pregnant, there might be concern she was just getting married because her parents were forcing her to, for family appearances. She's not entering it freely so it's not a sacramental marriage. (This is usually misunderstood in modern day as the priest being a meanie who won't let the two lovers get married because Church is prudish, but it's really meant to ensure the woman isn't being coerced).
You didn't say you were Catholic but Catholic ideas about marriage have an internal logic by which sacramental marriage is meant for the good of the spouses and to be a witness to the love between the persons of the Holy Trinity. It's explicitly religious and is designed to be lifelong but it's not meant to work like one party says "Hurr durr, I caught you in a Christian marriage now I'm gonna go do whatever I want and sleep around and be drunk all the time because you don't believe in divorce sucks to be you, hahahaha."
Hope that helps.