He is also a massive bully yeah he was bullied but that doesn’t give him the excuse to do it right back also he didn’t switch sides for moral reasons he switched sides because he didn’t think Voldemort would keep his word and spare Lilly he was willing to let her husband and not even 1 year old son at the time die if he had her all to him self and only switched sides because he wasn’t sure Voldemort would keep his word and only agreed to protect James and Harry as a afterthought