Love is ridiculously hard

So I love someone, trouble is, that someone is not my partner.
And I have known for years I don’t love my partner, not how I should, I know that I should be happy when I see them, be pleased to be sat beside them, I should want to be with them, but for years I have known that yes I love them, like a best friend, like a family member-And we do have children.
But whilst for years I have just gone along, making them happy, I am not, and worse now, I want to be with someone else. Someone I think likes me too. I see a life there, one I would be happy with, but I am weak. How can I hurt the one I am with?
So my thoughts are this, first find out about the other person, if they do feel for me what I feel for them, not rush into anything, we have known each other months now, and still it is electric, we love being around each other, share interests, share the same humour, music, books, even movies.
We have shared secrets, what we have not shared is sex. Nor will we, for numerous reasons, if we were together of course yes, but my thought is, find out if the depth of emotion in me, is shared, spend more time to really learn more, be around each other and decide, do these feelings hold.
Now, if they say they like me but not that way, or not enough for a relationship, fine, move on remain just friends.
But, if they do want to be with me too, then what?
I can’t seriously destroy someone can I, but on the other hand, do I want to watch this other person accept we never will be, then go on to be with someone else and worse, as I work with them, have to see and hear about it, and know I could have been that person?
I am angry, angry at my own weakness, I should long ago have pulled off the band aid, said, we are not right, I can’t do it.
Am I so horrid that I want to love someone I do love properly and be loved by them, to build a life, be married to them?
But I feel so awful, to even think of leaving who I am with, to hurt them, yet this rages inside me, I cannot feel good, every day I want to come home to someone else, but I care for my partner so much that it sets an internal war going I don’t know how to move forward.
And yes, I think of the children, but they could manage, we are neither of us the type to hurt the other with using them, besides which, even if this other person doesn’t want me, should I now face up to life as it is, rip us apart and then at least be able to be with another person, or no one if that is fates path, but not feeling wrong every day?