Better to be separated and parent separately than to be together locked in your own miseries. Whose sake are you really staying for; it could be argued that you are staying for your own sake rather than theirs.
As our children grow older, they tend to replicate relationships similar to what their parents modeled. As parents we’d never say we want our children to suffer or struggle in their relationships. Yet that’s the greater likelihood. It’s not what we say, but what we do that matters. Telling our children they deserve healthy, respectful, and loving partnerships isn’t taken to heart if we don’t have the courage to live up to our own words. What we model for them is very much what we might expect for them in their future relationships. From this perspective we might question the sincerity of the expression “for the sake of the children.”
Living in mediocrity or worse burdens children with very confusing messages about relationships and happiness. It certainly instructs them that loving marriages and partnerships are not their birthright.
There are many examples on here and from other sources of people staying together for far too long for their own reasons, mainly the children. Some say they will wait until the children go to university before leaving; this course of action is a huge mistake. Waiting for the children to go off to college/uni/leave home and then divorcing may make the kids feel guilty that their parents sacrificed their own happiness for them. We owe our children much more than the physicality of an intact family. We owe them our truth. Its a testing time for young adults as it is when they first leave home and they seeing their parents separate at this time further pulls the rug out from underneath them.
I would urge you to make the break sooner rather than later. Staying in a mediocre relationship also teaches them that your relationship with their dad was based on a lie and its a terribly heavy burden to place upon them.
Having two parents successfully move forward with their lives teaches an invaluable lesson: that we deserve to be happy and to feel loved. Conversely, remaining in relationships that perpetuate anger, devaluation, and lack of positive interactions leaves an indelible scar on children.