Considering the only girls putting big numbers are Adele, Taylor & Beyoncé, I'd say 100-150k, it will all depend on the first single, if it bombs then I may lower my predictions.
No tea, no shade but if Gaga starts the era with a decent bang and with a decent MV without setbacks or cutoffs and tries enough, she will surpass Britney. I see her opening with her album, 245k first week, if not 200k.
Sales are tragic these days, but the fanbase should be strong enough to push it around that figure. She might go above that if the first single is well received.
Obsession is a really really really serious mental desease. You shoud look for help.