Is it okay to leave a job off my resume?

Is it okay to leave a job off my resume? The company I worked for 7 years and got three promotions at (in project management) shut down :(. I scrambled to find another job in the same industry the next month, but it was at a 4 person small business and in sales. Long story short, the owner hated me, she behaved with poor morals and also even cut my salary one day. At that point I knew I had to find another job and at a large company in my project management role. I was successful in that search and left. I’m still at the same company but considering job searching again. That said, is it going to hurt me if I leave my 9-month job in sales (same industry) off of my resume?! First of all I absolutely hate this place, regret working there, and honestly never want to see or hear their name again. Second of all, while it could be relevant because I sold one thing that I ended up project managing, the owner HATED me.. I have no doubt she would make something up and talk bad about me if someone called to verify I worked there. Even if it could Mean getting sued or she’s not supposed to. Is leaving this off my resume going to hurt me?! It would show my current job (1 year plus months), 9 month gap, then 7 years of ongoing employment, 2 years before that of ongoing employment.