Can I swim without a tampon if it's my first period in my life?

This week, I unexpectedly had my period. My doctor said in about a year, but she was wrong. Now, I have a pool party tomorrow and I already said I could go! I don't want to cancel because the party is being thrown by a close friend of mine. I just bought pads but my mom said I would have to wear tampons! I don't want to wear them because they seem hard to put in and very scary. I need help!