salsa the "hell" you are going through is called your conscience and it wont go away whilst you are in this triangle.
Quite simply you can't have it all! you have to chose while you still have choices you may soon find your dh makes those choices for you- abd decides enough is enough he's not prepared to be second best.
I've been in his situation (my dh had an affair)have a look at the other threads going on at the moment about affairs- I and many others talk about the pain an saddness an affair brings to a family and the ripples go out from there- wider family get hurt too and friends and work colleagues, when an affair is discovered and the other party wants it to stop you only have so long to do just taht or decide you want out of your marriage before your dh will make that choice for you.
I know when you love someone so much you will stand by them through the trauma of an affair- that love will only sustain you so long- and that only helps if the partner starts to realise they need to stop the affair and focus on their marriage and children.
I suspect from the directness of your posts English is not your first language?If I'm right it accounts for the harshness of your words and the harshness of many of the responses. You seem to be asking for support or permission to carry on this triangle- you wont get that here. You will get support like others have, if you are saying you want to stop and are struggling...there are others in your situation and you know what is common for each of them is they are not happy in the situation they are in....so make changes- you are an adult, you make decisions and have to live with the consiquences of them. The sad thing is , is that so do the special people in your life and they may have no control here....you do!
My dh like you thought the other person was fantastic, special etc but he finally realised he was living a fantasy a bit of escapism from day to day life. What he had with her was not real or sustainable it was a powerful ego boost, a quick fix to the gap in his life at thet time it could not surrvive reality and when it all came out the relationship crumbled like sand as it had no firm foundations.You my dear will be no different- you can't see it now you are tied up in the heady powerful boost of a new, exciting relationship but those days are short lived, they will hit reality and the true nature of your relationship will come through. I think you'll find that what you have with your dh is far deeper, stronger, sustainable than this quick thrill with this other man.
The choice is yours (at the moment)end your marriage, maybe lose your family- go with the OM or stop ALL contact with him, focus on you and your family and dh and make cjanges to bring you all happiness.
What is an absolute certainty is that the "triangle" will not last and will bring everyone (including you children) lots of pain and sorrow.
Good luck with your choices.