Jackson put the proposal on display in new legal papers filed in her nuclear war with her ex-fiancee ... which shows how Floyd tried to convince Shantel into getting engaged for a 2nd time.
"This is what I offer to you. Let's get married move in together you can go back in forth to L.A and stay at the condo."
"I promise I will get you in 3 A list movies this year and I'm willing to go to counseling to make us work and you can get the stuff you want and I'm willing to change but I need you to have a better attitude."
How romantic, right?!
Shantel says she shot down the offer (shocker) ... and included several text messages dating back to April 2013 to show why Mayweather wasn't exactly her knight in shining armor.
Among the highlights ...
-- "I had your phone traced. I hired a detective. Your not slick."
-- "I got nasty videos too that I can put on Instagram and twitter"
-- "I took you from rags to riches now you back to rags bitch. that's why your out selling shit going on petty ass auditions fronting to people like your doing big sh*t."
Shantel also says Floyd got upset over a photo of her with rapper Nelly from April '14 ... with Floyd texting her the picture and saying, "Just tell me this didn't mean anything."
In the legal docs she also claims, "[Floyd] threatened that if I didn't take down the photo of me and Nelly, he would post 'naked photos' of me on social media."
BTW, Shantel and Nelly began dating ... and are still together.