AIO (TW NSFW) for mentally blocking out anything associated with oral s*x

i am on a burner account right now. a bit nsfw but me (20F) and a guy i’m seeing (21M) were doing things. we decided to do oral as usual but this time i’m not sure why but i didn’t want to swallow. for context our relationship between each other is mostly sexually and i quite often don’t open up to him. anyways this time i just didn’t want him to finish in my mouth this time and he says okay but as it went on he kept asking. i said i didnt wanna swallow about 3-4 times and finally caved bc i figured no big deal yk, and it’s easier to clean up. well right after this i started to black out mentally. idek why i reacted this way bc it isn’t something new. ive done this before but i felt like i completely disassociated. he noticed it and i just told him i was tired for the day and went home. fast forward to recently, we are fooling around again, i told him it was okay for him to finish in my mouth this time but once again i completely blanked out and disassociated for the rest of the night after, even tho i agreed that it was okay without repeatedly being asked. i’m connecting the dots now and it seems like mentally i cannot handle that anymore but idk why. i’m scared to tell him and open up about it bc i don’t want him to feel like im accusing him of assault or anything and i don’t wanna ruin the fun for him by doing this bc i easily could have gotten up and left in both situations. he’s been falsely accused of abuse and sexual assault before and the last thing i wanna do is make him feel like im blaming him for doing smth evil and open up old wounds. i just can’t handle it mentally now. should i tell him or get over it? is this blown out of proportion or is this something serious?