Yeah I think given your history you'd have a tough time pinning the "fault" for the D on her. Basically your argument would be "well yeah I did those things, but she did it worse so it's her fault!" A judge is likely to say you were equally at fault. But see what your L says.
Regarding the locks, "legally" you can't change them. Plenty of people here have anyway. Most WAS's don't bother to find out what their legal rights are, they figure once they leave they don't have the "right" to go back so if the door is locked then they leave. Legally they can call the police and demand entry, but I don't think I've heard of that happening here despite a lot of LBS's having changed their locks.
