At some point, you have to look at the actual situation, rather than whimsical dreams.
Even if we absolutely accept that she loves you, she loves her husband and children more. To the extent that she will not share her husband with you. She has an arrangement that suits her perfectly, she sees you a few times a year, the rest of the time she is happy with her family.
This does not work for you. She has told you that she does not see a future without her husband in it. You need to accept this - not argue it, or hope that she changes her mind, or ignore it - actually accept it. There is no future for the two of you in a monogamous relationship.
You don't want a polyamorous relationship. I don't think it would work anyway, I think you'd end up jealous and hurt that he comes first. So this doesn't work for you, there's no way forward.
At some point, you rip the bandaid off. Until then, you just carry on going, having some good days and some terrible ones, until the terrible ones outweigh the good ones or she leaves or something else happens, and suddenly it's off. And then you deal with the pain, because it will hurt, but you start to heal. Rather than being in some kind of strange limbo where you know you're believing a lie but you don't want to let it go, you start to recover and make a new future.
The problem occurs when you either refuse to let go and make yourself so miserable that you can't see a way out, and then have to go through the pain anyway but starting from an even lower ebb, or you wait too long and waste the future as well as the past.