Friendship in jeopardy!! help!!?

ok so i have this friend and her and i had a little disagreement. And that was no biggy, but she keeps wanting me to go to the beach and go swimming, but i feel uncomfortable in a bathing suit, and she just thinks i don't wanna hang with her, but im to embarred to tell her the real reason...and its wrecking our friend ship, and any one please help!