I was reading this thread wondering how long it would take for the worm to turn. Reason being, it was turning for me too.
OP, I'm sorry to hear about the breakdown of your marriage. I am not going to call your ex anything derrogatory; there has been ample of that here already. I think that he has handled it poorly, he has not treated you with respect, but I also believe that each and every one of us reserve the right to be happy in our relationships. If he, for whatever reason, is unhappy with you, he can and should move on.
In respect to finances, I'm with those who feel it's time to wake up and smell the coffee. You have been very privalaged to live the life you have. You have been able to stay at home and raise your daughter without the need to work to near adulthood. In a lot of ways you have been luckier than most. Those days, however, are over.
Your ex has committed to continue to support you. Great. I wouldn't depend on this lasting forever though. If I were you, I'd be using the coming months/year to work towards financial independence. As it should be for every woman in my opinion. Never, ever, depend on a man to fund you.
As for the train of thought running through the thread that she should take him to the cleaners, expect him to live in squallor, leave him on his uppers; I don't agree. He works, he earns well, he should be able to live as well as the OP. That, to my mind, is fair.
The word fair is hard to use as the situation the OP finds herself in may not be fair to a lot of us. But, you know what, life and particularly love, isn't always fair. For now, you need to protect yourself, absolutely. But paddle your own canoe, OP. You'll feel better about yourself and this experience could potentially leave you feeling more empowered than you've ever been.
The other thing that struck me reading through your posts, is your wish for your ex MIL to 'honour' you. I believe you have had and will continue to have a good relationship with her. But never forget; blood is thicker than water. I find it unreasonable that you would expect your ex's mother to live her days fighting your corner at the expense of her own relationship with her son. I'm sorry, I do. If the shoe were on the other foot and your hypothetical future son in law expected the same from you, I would hope you would always support your daughter, irrespective if you always agree with her decisions. Your ex is now living with his parents. That alone is indicative of the fact that they will continue to offer support to him. You can't expect them to never meet future partners; whether they be the current GF or future ones. It is unrealistic and I fear you will feel huge betrayal over this matter in the future when your MIL doesn't see through her promises. Prepare yourself.
The other (and last thing, promise!) that I felt was the way your daughter has been placed in all of this. I couldn't understand why you involved her so early on. I felt that irresponsible. I'm not blaming you. None of us know how we're going to react when our world comes tumbling down. I just didn't feel it right to involve her in your marriage. She is now firmly on your 'side'. And for now, that will most likely please you. However, again, be aware that this will not be the case forever. I would hope and I think you should also hope that she and her father are able to salvage a relationship when thing die down a bit. He was unfaithful to you. Not her. Now, there is a school of thought that unfaithful spouses cheat on their partners and their children. I'm not in that school. It is possible to be a loving parent while not being in love with the child's other parent. Just my tuppence worth on that one. Don't poison her against him. She will become aware in years to come. I'm not saying you will, but just be careful on that one.
We all have one life. Your ex is living his now. The very best thing you can do is the same. I wish you luck on your new journey. Mind yourself. Sorry for the novel!