It does sound like you need a break. Do you have any friends or family that can take care of the children? Did you or your husband take care of them in the past separations (if it was you, try and see if the husband can take them this time)? Just don't give up hope, and don't let a separation become an excuse for divorce.
I am part of a loving group of Christians who have been giving me counsel and guidance and much prayer. We have been in counseling with people who have been committed to helping us put our marriage together.
It sounds like you have put in a great deal of effort and are on the right path to resolution. All you have to do to make the marriage succeed is not give up.
I will remain in counsleing as long as it takes until the marriage is fully dead, a negotiated companionship, or revived.
As long as you two don't give up, the first option won't happen. There is no way to tell how long the struggle might take, but if you don't give up hope things will improve.
But after many years of living a life that is alone I am also wondering whether there will be a future for me without my husband.
No doubt there would be, but it simply would not compare to the quality of the life you deserve with your husband and children. From the sound of things, you have struggled with this problem for a very long time, with no apparent improvement in the situation. Even so, don't give up. Usually things look their worst just before miracles happen.