Olivia's younger sister posted multiple alleged text exchanges and pictures with the Miami Dolphins wide receiver from as recent as February ... which would debunk the NFLer's timeline that the two decided to call it quits a month prior.

In the convos posted to the model/influencer's TikTok, SC and BB appear to be on the rocks ... with the two seemingly discussing the public speculation surrounding their relationship. Berrios' responses make it seem as if he's willing to work through their differences ... reassuring Culpo he will "do everything in my power" to make sure the situation doesn't blow up any further.

The most explosive allegation came in Sophia's caption of the post ... where she says the couple broke up following the Drake concert during Super Bowl weekend when Braxton was "seen making out with another girl."

As we previously reported, Braxton went to Instagram to defend himself earlier this week ... saying cheating was not a factor in the split -- despite rumors he was seeing TikTok star Alix Earle while he was still dating Sophia.

Culpo seems ready to put the drama to bed ... saying, "Not bitter, in fact I know this situation has been one of my biggest blessings."