Jesse James appeared to back his wife Bonnie Rotten in a cryptic message Tuesday ... after her arrest, following his accusation she assaulted him.

Accompanying a photo of Bonnie in front of a hot rod, Jesse posted, "The devil doesn't always come with horns -- sometimes it shows up exactly how you like it."

Awww ... How sweet! Her charge was pretty serious, though ... he accused her of striking him -- leaving marks on his face and neck -- and biting his thumb Saturday.

As we reported ... Bonnie -- real name Alaina James -- was arrested and booked Saturday on a charge of assault causing bodily injury involving a family member.

Jesse told police Bonnie struck him in the face and gave him a black eye ... and he had the marks to prove it!

Bonnie later confirmed to TMZ that despite whatever their differences were, they're still staying together ... "This was an unfortunate situation. Jesse picked me up from jail. We love each other and want to make it work. We had a quiet family night at home and are seeking help in areas we need and will have no further comment at this time."