Once they are married, the separation will happen naturally. Don't overthink this. If you have plans with your DH, don't break them for your children unless it is an emergency.

wow, this doesn’t sound unhealthy to me at all. seems very normal, but I’m from a large Latin American Family and what you describe is not abnormal. Only thing abnormal is your therapist and the fact that you are american and close to your children. Most Americans in my observations have a unhealthy disconnect with their families.

The sooner parents can view their adult children as peers, the better. It's the only way the adult child has the respect of the parent. Without that respect, the adult child in crippled in life. The adult child has to be financially independent. They can not live any part of their live afraid that something will be taken away - they will manage if it is. Neither party can be too afraid of saying the wrong thing. An occasional overstep of the parent/child is treated the same as with any other adult you care about and wish to keep in your life.

*If you are blessed to have resources to do so.