Wear something that fits well and that you feel comfortable in. Don't take this wrong, but who gives a d@mn about him, right? It isn't about showing him anything. It is about you feeling confident, strong, ready to face whatever happens and move forward.
I, personally, have always been taught that you "dress up" for the important things in life so I think a nice sweater and some slacks would be fine, if you have those and would feel comfortable in them. I would be careful with the baggy stuff, though, because you don't want to look sloppy or like you don't care, unless, of course, the pants you are wearing are supposed to be baggy. If they are not, I'd invest in a new, better fitting pair.
Me 52, H53 Bomb drop 9/29/2014 Divorce from XH final 12/17/2014 Marriage #2 12/31/2019 5 adult (step)daughters (3 from XH's first marriage, 2 from current H's previous relationships) 6 grandkids