Farrah Abraham is crediting ketamine for helping her squash her beef with Jenelle Evans.

The "Teen Mom" star tells TMZ ... ketamine therapy is helping her move on from past traumas, and it allowed her to have a clean slate to start fresh with Jenelle after years of nasty feuding and drama.

Farrah and Jenelle made nice last week over dinner in Las Vegas ... but she says it wasn't the Mexican food that got her to give Jenelle another chance -- it was ketamine.

She says she's been doing ketamine therapy for a while now ... and she wiped the slate clean with Jenelle and wishes her and her children all the best moving forward.

Of course, Jenelle played a part too, reaching out to Farrah to congratulate her on her stand-up comedy debut at the Spearmint Rhino Gentlemen's Club in New York City.

Jenelle's going to host a divorce party at the club next month, and Farrah tells us she's hoping to attend.

Another "Teen Mom'' star who has feuded with Farrah over the years -- Ashley Jones -- was also at the dinner in Las Vegas and Farrah tells us how the two ladies smoothed things over.