I guess "sick" is just easier than so many others:
"unwell" "not thriving" "poor coping skills" "lacks sufficient tools" "suffering from neglect or wrong-doing" "partially insane" "mentally unstable" "co-dependent"-- they all work, grab your own. but we'll never be able to control the term that suits everyone else. If so many "like" sick, well, then, the most rational thing would be to a)get used to it b)ignore it c)correct everyone as to what is more preferable to you on on-going
Good luck and try not to let it drive you "partially insane" LOL