Really struggling!

Im really struggling! Ive been married for nearly twenty years, and if Im being honest Id say Im at a point where Im terribly unhappy with my husband but I cant imagine how to move forward. We live in Australia but he is from the US. We have three kids, one who is 10- hes sweet and loving but mimics his dads rudeness too, one whos 14- he is lovely and has a lot of anxiety, and one who is about to turn 18- she lovely and has just moved back home after finishing high school interstate as we moved a year ago, and so shes brought her boyfriend to live with us too so they can go to Uni. I work full time as a school principal and love my job, Im doing a masters degree part time (my third- I love studying). Ive also recently been diagnosed with MS. Fortunately its mild but Im very conscious of the role stress can play in disease progression. Ive seen two psychologists in the last 18 months who have both suggested may be better off to leave my husband, and Im going back this Friday for an appointment and my husband wants to come. Weve been to counselling together before and nothing seems to change. If you were to meet him youd think he was a friendly, funny guy. Hes a great flirt and charmer, hes a good looking guy, but hes very rude and irritable so often at home and has been for many, many years. He barks order at the kids, is very hypocritical- he will sit on his computer for hours, and then when Im on mine working, hell make snide comments