Most Helpful Guy
Tricky situation no doubt. Seems like you have been through a lot of tough phases in this relationship.
I would definitely say that you by no chance should give up. If you have been together through all this, divorce, cancer, business booming (I can only imagine all the drama). This shows that you guys have a strong bond, a good platform and that you care deeply for each other.
This has to do with his conscience, not yours. In other words, this puzzle is something he must solve on his own. I know this is something you recognize since you guys are definitely a good team at solving life`s challenges together. But this one leaves you in a tough spot - what can you possibly do?
Well, the answer is two-fold. You can`t do anything to change his feelings towards the children and ex-wife, that`s for sure. Ask, but you can`t tell. But what you CAN do is to look after yourself, be honest with your intentions, your needs and your feelings.
If the hammer drops and he will prioritize differently, either moving back with the crazy one or finding something new, then this is his choice. Not yours. You know what you want - there is great strength in this (!), it is also an attractive attribute among both genders - to have a firm and clear goal.
You have not lost 14 years, you have gotten 14 great ones! 14 years of love, love for a man who has been through tough times, and become stronger because of your support. I would suggest that you continue to give that support also in the future, make your man stronger, as long as he is yours. Show your strength and thus motivating him to make the right decisions. For himself, and for you.
Regarding the marriage, I feel that this is clouding the situation. So I would remove this "extra baggage" and make the situation less complicated. There is no hurry, you can marry later, the children will get more "relationship experiences" as time goes by, and then they may recognize first hand that life, and especially love-life, is not always simple.
I would however be honest with the kids about this, and that your fiancee sits down with them and tells them that you are putting this on hold to show respect for their feelings (even if those feelings are influenced by crzy-mom). This will show them that you actually care a lot about their opinion, and that you want to include them in your "happy moment" in a good way.
Summary: Be the rock that he needs, as you have been for 14 years. Honestly I think you`re doing great, just keep it up!