Should I have done this?

All right so now i feel really bad... okay. Well my older sister is friends with this really nice dude and his ex-girlfriend kept calling him and i guess she was being mean to him, but idk the whole story. So anyways, he wanted my sister to call his girlfriend and tell her she was dating him so she would leave him alone. Well my sister couldn't do it so she asked me to, and i mean idk either of the people so i was like sureee i guess i will.. and i did. and my sister wanted me to be bitchy but im nice and like being nice to people cause im a goody good (and im proud) but yaaa she was a little bitchy on the phone cuz she thought i was actually his gf and she's like "ooo r u getting jealous" and then i started going on like i was actually his gf. and after i hung up on her i felt sooooooooooo bad cuz i didnt even know her, i just dont do that type of stuff but he was happy and he said im awesome and blah blah blah but yaaa i just dont know.... was it okay that i did that? and if it helps im a christian girl so thats another reason why i like being good to people!!!!! its bothering me i wish i could say sorry but i dont even know her number!!!! HELP ME!!!!