Tell or don't tell?

Cutie🧚‍♀️
So I've become sexually active and I want to tell my mom but I don't want her to freak out. I have no idea how she'll react to it and I don't want to not be able to see my boyfriend anymore. Normally my mom is very chill about stuff but she's been over reacting to a lot of things lately and I'm not sure what to do!