If you washed your hands well (as most emets do) and you did not let him prepare or handle your food, you probably were not exposed. Try not to worry.
Many people swear by purple grape juice as a sv prevention tool. I have my kids drink a glass a day this time of year. If you are really worried you could drink a couple of glasses. It has to be the purple kind though.
Sv is not worth dying over. I promise you it is not. It is scary. It scares all of us more than it should, but it is not worth your life. I hope you will reach out to someone in your real life, or call a helpline, if you start feeling desperate.