Hello, and sorry you find yourself in this situation.
First, know it isn't your fault. Your husband cheats because he has issues and he has some really poor coping skills. Cheating is a very easy way to make oneself feel better, and that's what he's doing.
Your H is a serial cheater, meaning he continues to be involved in affairs over and over and over. He most likely will NOT stop without some serious counseling. Is he in counseling now?
As for you, I think by now you know that your H won't stop cheating. As this is his 5th time, you've basically given him approval to cheat. There have been no consequences, he's lost nothing. What reason does he have to stop?
As painful as this is to admit, your pain won't stop him. You know that. You've been through this 5 times already. He may feel bad, but the good feelings he gets from cheating outweigh the bad feeling he gets from your pain.
You need to decide if you can live with cheating, or if you will not tolerate this. You need to decide what your boundaries are, and stick to them. If you do nothing, this will happen again. This is all but guaranteed.
You wrote OM several times, but I think you meant OW - OM means Other Man, OW means OW. OW doesn't care about you, or that he's married with children. She was humiliated when you confronted and she had to ask for her things from the house. And yet, here she is again. She's a predator - she is out for herself.
Is OW married? If so, you should tell her BS. Her husband deserves the truth, and it will most likely force her out of the picture.
Even if OW exits your life, your H will find another. Again, 5 times tells you there will be a 6th.
It's your choice at this point. What are your boundaries? What will you accept in your marriage and life? What will you not tolerate?
If it were me, I would demand he stop cheating immediately, and that he enter IC - at least once per week. If he will not do that, then I would tell him he needs to live elsewhere and I would begin divorce proceedings immediately. Again - no consequences = no change. You filing for divorce may wake him up. If it does, great. He can go to counseling and you can try to heal together. If not, then you've saved yourself more years of cheating and heartbreak.
What I've suggested is scary. It's life changing. It's hard. But as is often said here - to save your marriage, you have to be willing to lose it.
When it becomes hard, remember that your WH's actions are the example being set for your children, as are yours. You are telling your kids with actions that being disrespected and lied to is acceptable. He is showing them that lying and cheating are fine. That betraying loved ones is fine. That selfishness is fine. You know these are not things you want your children doing, and yet this is what they are seeing.
I'm NOT saying you are being a bad parent, at all. When in such a traumatic situation as being betrayed, it's hard to see all the angles. Your kids' perception of acceptable is probably not what's first on your mind. If you think you've kept this from your kids - you most likely haven't. Kids are far more perceptive that we give them credit for. They may not know the details, but they probably sense something is wrong.
Please, take a stand and demand better for yourself.
And yes, some will simply question why you've stayed. It's an easy question to ask really. The answer is that, despite the pain, you love your H. We all loved our spouses when they cheated. And love doesn't end at betrayal. If it did, as I've said before, this site would not exist. We would be betrayed, instantly stop loving the betrayer, get divorced, case closed. No hurt, no healing, nothing. Love grows over time, and it takes time to die.
You will probably always love him in some way - he's the father of your children after all. However, that does not mean you have to accept this horrible treatment. Loving him is destroying you.
Boundaries - what are yours, and how will you enforce them?