What exactly do you love about him?
The way he has showered you with affection?
The love and appreciation and thanks he has given you for looking after his parents.?
Perhaps it's the time and Care and money he put into showing you how wonderful you are.?

Maybe you love the way he treated you when you confronted him about his lover. Or he way he left you financially destitute. Or maybe it's the utter b.s and lies he told about you that make him so endearing.

And now his mistress have dumped him,because she at least has got wise to him and realises he won't treat her any better than he,has treated you.
His beds getting cold so he is giving you a call to try his luck.
Sure it might work, if he admits his part in it, comes home. Doesn't work away anymore, because I promise you he will do it again.
How do I know that?
Because there are no repercussions for his horrendous behaviour.
You have laid down and quite literally allowed him to walk over you. You might dress it up as strong d determined. I can assure you he will see it as a weakness at treat it as such.
Enjoy the apologetic stage while it lasts, because unless he has a reason to change he won't.

One last thing. You take him back, that's it. You can never bring up the affair and use it as a stick to beat him in an argument.

To be honest, I would not want to be with my fella after he had been sticking it in someone else.(apologies for my crude terminology, but it is what it is.)

Anyway I actually wish you all the best, good luck trying where so many others have failed.

Oh...One more thing, is it really that you love and cherish this man or that your more afraid of the unknown?
That your too afraid to start over? Nothing wrong with that,but at least be honest with yourself if that's the case..
It's much more likely to work out if your both honest about why your there.

All the best, Take care.