You do not owe anyone an explanation. Your situation is extremely common.
Bide your time. Play your cards close to your chest and keep your exit plan private yet, mindfully ever present.
You are doing your best to raise your children in a loving, stable environment.
You are a mother first and foremost.
There is nobility and integrity in your role as a consistent, caregiver (to 2 children one of them Autistic).
There is nothing naive or weak about being committed to ensuring that all your family's basic needs are met--as much as you are able to do so in your capacity as a wife and mother (presently healing from knee surgery).
Is it untenable? Does he beat you--leave you and the children without a heated home food and clothing?
Unless you are holding a lot of information back the answer is NO.
But, you do have concerns and you should be able to freely express your concerns without enduring confrontational, rigorous inquiries as to why you are still in your marriage.
Feel better, allow your knee to heal. Bide your time and strategize an exit plan you will begin to unfold within the not too distant future--but only when you feel you are ready to initiate your transition.
Most importantly know the law. Understand your rights. Do not do anything impulsive like leave your home because were you to do so the laws may not be in your favour.
Security is important. No matter what in a marriage assets, property and liabilities are 50/50.
Even if you have never worked outside the home, half of the property and assets are yours and in that sense many women treat marriage like a business or career at least until they are able to diversify and move on safely knowing their children's needs are met and will continue to be met.
Women have left their homes for legitimate reasons yet still been sued for abandonment.
Talk is cheap. Advice is cheaper.
You don't owe anyone but yourself and your children. For now your husband is a valuable resource, contributor and co-parent.
The marriage is less than ideal but the home is stable and his income is steady.
You know what you are doing.
You are allowed to question, rant, vent, speculate, dream-whatever you need to do to feel empowered, optimistic and meet every day as a mother with hope and love.
For now that is what is needed. Am I correct?