from www.tmz.com – TMZ has learned Lorenzo Lamas went absolutely ballistic on Shauna Sand this morning — unloading a verbal assault on his baby mama over her sex tape … but unlike the porn, it was Shauna who got the happy ending in this story.

It all went down at Lorenzo’s house — after Shauna dropped off their three young daughters, per the former couple’s custody agreement. Sand tells TMZ Lorenzo was furious over the existence of the sex tape — and Shauna was extremely worried that the “Renegade” star would wage a legal fight to get sole custody of the kids.

But Sand claims he eventually calmed down, told Shauna that she was a good mom — and promised not to battle her for custody. To prove it, Sand says Lamas grabbed a pen and a sheet of paper … and drafted the following statement:

I, Lorenzo Lamas, will not seek custody of my minor children with Shauna Sand.

Even in the event of a release of a sex tape with her and her boyfriend.

Lorenzo Lamas

Lorenzo was unavailable for comment.