Whatsapp!!!!!!!

So me and boyfriend broke up and he didn't have whatsapp! I was just on my whatsapp and see he's number come up as on whatsapp so I messaged it! He read the messages and then by the looks of it blocked me! We have kids together so I rang him and said how comes you just blocked me on whatsapp after reading my messages! And he is claiming he didn't and doesn't have whatsapp!! What do you guys think do you think he's just trying to brush me off or can someone else have a whatsapp connected to he's number??? The break up was recent as in last week! I don't want no replies about your not with him get over it I just want to know what you lot!😁