If you are enmeshed in something, you are caught in it, like a fish in a net, and it is hard to pull free. The something is usually a messy, unpleasant situation: a family fight, a court case, a war, a web of lies. We almost always say enmeshed in …. It is more a writer's word than a playground word; in speech people often say caught up in or stuck in. Though actually, some people also stretch it to a relationship that is too close and tangled, where nobody has enough space — same picture of a net, just a different kind of trap.