Proof that the hadieth about a woman taking her clothes off outside her families (husbands)house is not strong?

Ok so i want to go to the YMCA with my friends and go swimming there and it's only girls in the whole building no guys allowed and we also asked and there are no camera's but the problem is that my dad says that women are not allowed to take their clothes off outside their house. I know this is a hadeith but i'm pretty sure it's a weak one from what i heard. I mean what if your at a friends house and you wanna dress up and wear a dress or something when it's only girls, there is no problem with that. So i need PROOF that this hadeith is a weak one and that i can go swimming because there are no guys and there are no cameras PLEASE HELP!!! 10 POINTS FOR BEST ANSWER!!!.... i need a link too if you can! thanks