I'm not going to tell my abusive ex that I'm not pregnant
Did you tell your ex that you are pregnant?
My ex felt pity towards me when I did. I hate it but I need payback.
You shouldn't create new drama from people in your past like your ex. You're going to play with their emotion and they will not like it, nor will find that kind. I would suggest you talk with them and end things in a more positive note, rather than being so toxic.
I don't give a shit. I'm going to do this thanks.
Your ex will eventually find out. Do you want to be labeled as a woman who lies about pregnancy?