Boys...

So I am 12 years old and started tracking my period a little while ago.But on Friday at school I had PE first up and I didn't want to tell a male teacher I was on my "Ladies Days" so my mum wrote a note saying I had a sore knee.And I got away with it but a boy asked me what was wrong and so I said I had a sore knee and he said that's not the only problem is it.So he walked back to where he was standing with the group of boys he hangs out with and my crush is apart of that group so he asked me again what was wrong so I told him I was on my period and my crush heard and so did all the boys and I heard them talking saying they have to treat me nicely.Should I have told him??????