Lou -
If I know anything about educational institutions, big or small they are all hotbeds of gossip, and someone knows something about everyone.
Let key people know your STBEX "you know who works in "
has left you for another woman, possibly a colleague, and the affair has been ongoing for some time.
No need to elaborate on this part or either of the pregnancies, but make sure they know how he left, and keep up the stiff upper lip approach.
It will get out, and the OW will hear about it, which is why he was so desperate earlier to know who you have told.
I know it may sound petty but why does he deserve to be treated with any repsect after the way he treated you- I can understand you wanting some answers even if it upsets you. Once you KNOW the whole story you can desal with it, this drip feeding is torture.
Bug hugs you are so brave, great to hear your solicitor is on your wavelength, having one you trust & feel comfortable with is a key thing.