Help please

Long story short, my brothers girlfriend cheated on him and she has now asked for her belongings back which myself and my brother delivered to her new boyfriends house where she lives, she is now clamming that my brother has stolen a coin that was her uncles and I am now getting texts saying her and her new boyfriend are getting the police involved because it is classed as theft and because I sent her a text saying stop with her attitude towards my brother! Can the police do anything, what will happen I’m also being told I can get done for domestic abuse cos of the text I sent her