You can't, Mums know everything.
just dont tell her LOL
Don't do it in the first place!! Be woman enough to tell your boyfriend you have moved on and don't feel a connection anymore.
Say, "I will never cheat on you."
== ==
"You broke up with your boyfriend and he said that he doesnt really care are he cheat on you?
Ask your boyfriend. I'm sure he has some ideas.
NOPEE
Best is not to have anything to do with him, once a cheat always a cheat.
You can put in the 'testingcheatsenabled true' cheat and then drag the relationship bar up on the sim you want to be your boyfriend, and then when the relationship between them is on 100 you can ask them to go steady after flirting a couple of times. Hope this helped :)
Leave him. If he's going to cheat on you your obviously to good for him.
Be nice and don't cheat on him