Malwarebytes is a good antivirus and the free version should allow you to remove most things there's also Microsoft security essentials or if its like a flash drive and there's nothing else on it you can format it too.
Its possible that he doesn't know how you feel maybe all you need to do is talk about it with him and let him know its upsetting you. Guys can be really insensitive at times so if you don't speak up he might not even notice something is wrong.