Friends with benefits with an ex

Last night my unofficial ex (we were never officially together) was drunk and basically told me he still has feelings for me but doesn’t know what and feels there is a lot of unfinished business between us, we’ve sorted out our problems and both established we have some sort of feelings for eachother. He wants to be friends with benefits which I am down for but said we can’t be a thing again but if it happens it happens and said it is still possible. Advice?