Well first of all... Invest in some firewalls man xD I use both a hardware firewall and then a software firewall to keep myself safe... Also use a VPN for any connections to the internet just in case.... You can not really prove based on what you have said that express actually did it. I am not taking his side but I am simply stating that the facts that you have laid out while makes it seem like he did it can not really prove that he did it. My advice is just to better protect yourself in the future so you can not be ddosed so easily.