All lives matter or black lives matter?

As a black girl who’s 17, it’s super hard to understand as to why so many people around me are saying the black community is doing too much or all lives matter.

last night, i was with my boyfriend (white) and his sister and her boyfriend and he raises the question “do all lives matter or is it just black lives?” and my boyfriend said “Black lives matter. If all lives mattered, we wouldn’t be doing what we’re doing today” which made me super happy.

Then, his sisters boyfriend says well... do rapists lives matter?” and we said , they do have basic human rights but i definitely could care less what happens to them (I was molested by my step father, so that upset me when he said that. not his fault though!)

so he said “it shouldn’t even be named black lives matter then. it should just be all races matter since this is about black people”

and it’s like, it’s so hard to come up with valid arguments to support his case since im so scared to speak my mind.