It's time for YOU, Mom. For 23 years you have been your childrens' maid-servant, cook, butler, nurse, chauffeur, therapist, and bank account. And you've done a good job. Maybe too good. ;) Being everything for everybody all the time for more than two decades is going to be a hard habit to break!
The very first thing that struck me about your question is not about what your kids are doing to you. I was concerned because it sounds like you don't have the support from your husband that you need in handling the kids. Your kids will model whatever behavior Mom and Dad - together - will allow. If Dad is disrespectful to you, that sends a strong message to the kids that it is allowable to treat you as a doormat.
I hope you can sort out your marital challenges first, and focus on those primarily at first. Put yourself and your marriage in the place it ought to be - at the helm of the family ship. Together, you and your husband need to unite against the kids and help them develop a plan ansd a timeline to get out on their own. If you and your husband are not of one mind, your home will be divided in chaos. And the kids will play on that. You will likely be unsuccessful in getting the kids out on their own if you do not have whole-hearted support, encouragment and partnership from your husband.
The years ahead will be about you and your husband, so I hope you will see it fit to invest deeply in your relationship with him, so your marriage will be there for you when the kids no longer are.
As long as you continue to focus on the kids, they will not learn how to focus on building their own lives.
Here's the tough part - if you are using your kids as an excuse not to focus on your marriage, or if you fear they will leave you and you will have no more purpose in your life, I pray you'll search through all that and find your own sense of worth outside your relationship to your children.
There is hard work ahead for you, and my heart and prayers go out to you!
Your husband needs an attitude adjustment, and so do your kids. But you can only start with YOU. What will you do today to treat yourself well?
Happy Valentine's Day - I hope you do something nice for yourself today - something symbolic - that sets you up for the positive new changes ahead!