Yesterday we finally found a solution of our problem.
After long talk and thinking we decide to be just good friends, we will still live together but we are free and can have some new relationship
As there should be finished house until winter we decided to make some changes in it and make two separated flats, each in one floor, it should be fine as each will have approx 2000sq.ft
Wife with children will live at first floor and have direct access to garden and I will have second floor.
So if everything goes as we planed it could be great solution.