Standard US Amazon link with no affiliate links afaik: https://www.amazon.com/Nice-Girl-Syndrome-Manipulated-Standing/dp/0470579900
I needed it too. It helped me everywhere in life... My boss actually suggested it because he got sick of me not defending my projects even when it was valid to do so.
You might take a look at the book The Nice Girl Syndrome by Beverly Engel. It has been out long enough that US libraries will have copies.
Amazon review list -https://www.amazon.com/Nice-Girl-Syndrome-Manipulated-Standing/dp/0470579900#aw-udpv3-customer-reviews_feature_div.
BTW, your BF has not forgotten that he has a living mother, his mother his job; does he organize gift giving for your parents?
I'm sorry this person did not respect your boundaries. I feel that the book, The Nice Girl Syndrome by Beverly Engel might be of use to you.