lingerie

Drives me mad as well, grannystrong. And what's wrong with 'underwear'?
Other irritating mispronounciations (did you see what I did there?): restauranteur and chocolateer (for chocolatier/chocolatiere)

So the problems with the ending ... Either a long A or a long E with the latter being preferred?

The closest I can get is lanje-ree. You sort of suggest the middle e and then roll the r. Granjura can probably do it better! Les linges are your linens and lave-linge is a washing machine.

Can I ask how it should be pronounced?

No, I don't pronounce it Paree either, but Paris is pronounced here as written; my objection to 'lanjeray' is the ay sound at the end - where does that come from?

I think it is perfectly OK to give French words adopted into English and Anglicised pronunciation. I live in France and speak French, but I wouldn't dream of using a French pronunciation of Paris, for example, when in England. Nor to I correct my French friends when they get English words wrong, though I laughed so much when I was invited to a Toopairwah party that I had to explain why.