Kinda, should i intervene though?
You are not in a position to do much intervention, and it is better if your parents keep it that way. If they do their duties, they’ll keep this off of your shoulders entirely. It is not your business to run their marriage. You will do your part if, as always, you support them when you can, particularly when you can see they are in particular need of it. By that I mean being mature about lending household help without being asked and general stress reduction,
not that you try to become a marriage counselor for your own parents! If you were fifteen years older and actually did marriage counseling for a living, that would still be a bad idea. Do not go there, do not go there, do not go there.
You can and should, however, encourage them to live the Catholic faith, the gift that they gave to you and promised to teach you, where you are given the opportunity. That would include refusing to have anything to do with anyone either of your parents choose to “date” for as long as they have not been declared free to marry by the Church. You do not have to make scenes, but you should let them know that you do not approve of what is unacceptable according to the faith they gave you. They may decide to divorce in order to be able to live in peace and divide their belongs amicably and justly; that is not your business, and they should not put that decision on you whatsoever. Unless the Church also declares their marriage was never valid, however, they are not free to “move on”. Now, if they divorce and decide to share custody, there will be a limit to how much control you have over that (that is, whether or not you can refuse contact with illicit relationships that they choose). Do what you can, do not become anxious over those decisions that Providence has not given to you, and especially do not waste worry on bridges that you have not been asked to cross yet. One day at a time.
For right now, though, insist on being kept away from illicit consorts such as “the other woman”, and encourage them to find competent help if they seem to need it. Don’t give it yourself, but do gently encourage them to find it.
Most of all, do not forget to pray for them and to pray that you yourself may never be put to such a test yourself, when it becomes your turn to live as a saint in the state of life you will someday have as an adult.