Hi, your girlfriend has caught you in a very bad situation. The deal is simple. You have to follow whatever I, her friend, says and may be she will consider not breaking up with you.
This tease needs a two-weeks preparation.
stuff needed:
-a box of XXL condoms (the bigger the better)
-a box of your tiny size condoms
-silicon based lube
-toothpaste
-clothespins
-rope
(-a chastity belt is better but not compulsory)