Lied to my mom about something stupid and now I feel guilty

I accidentally clogged our bathroom sink by putting a tissue down the drain. I genuinely thought it'd break apart and go through, but it ended up causing a partial blockage. A few days later my mom called a plumber, who fixed it.

She asked me if I had done anything to the sink, and I panicked and said no. She then guessed it was probably my older brother.

Now my brother isn't even home yet, but when he comes back she'll probably ask him too. He'll obviously deny it because he didn't do it, and now I'm worried either he'll get blamed or she'll realize one of us lied.

It's such a small thing, but I feel stupid for not just admitting it in the first place.

She might MIGHT also think the househelper(kaamwali) did it, well I hope cause she also left the house