In Spanish there is this saying "Candil de la calle, oscuridad de tu casa". Which is basically said to people who do good outside, e.g. at work or school, but does nothing good at home for his or her family. A literal translation to English would be something like "A light in the street, but darkness at home. Is there an equivalent saying in English for this?
street angel, house devil
It means exactly what the Spanish phrase quoted by the OP describes (though perhaps not "exactly" because it is typically used in reference to children, whereas the OP's question does not differentiate between children and adults).
It's common also to hear only half of the phrase used
He's a street angel
because it's assumed the reader or listener is so familiar with the phrase that the second half can be left unsaid.
Here is a recent example from a parental advice column in the Irish Times:
and here is one from a popular Irish parenting website, rollercoaster.ie:
The closest analogy I could come up with is Jekyll and Hyde, it expresses the dual personality of a person (this can be applied to both sexes but more often it's used for men). One day that person may be kind, sociable, and friendly; the next, tense, aggressive and generally speaking, unpredictable. However, the expression Jekyll and Hyde doesn't suggest that the person acts like a lamb outside the home, while indoors he behaves like a wolf.
Merriam-Webster defines it as
one having a two-sided personality one side of which is good and the other evil
- He's a real Jekyll and Hyde who can become violent without warning.
- his Jekyll and Hyde tendencies
EDIT: I remember hearing it being used for women, so I checked on The Big Bang Theory show (series 5 episode 1) and found a reference. The leading female character, Penny, has recently ‘slept’ with a friend of her ex-boyfriend (Leonard), and confesses candidly to Amy:
Penny: You heard what I did?
Amy: Well, I heard who you did
Penny: God I screwed up everything, I hurt Leonard, I hurt Raj. What is wrong with me? I feel like two totally different people, Dr. Jekyll and Mrs. Whore.
Obviously this is a play on words, and a punchline, but if you search in Google there are about seventy-three hits for this expression (click on page 7). And it still conveys the idea of a person who has a double personality.
They are erecting a superficial facade of altruism.
A deceptive outward appearance:
I've heard "prince in public" used to describe that specific sort of duality (rather than, say, someone who's "two-faced"). The phrase itself implies that this person behaves poorly at home. I'm surprised I can't find information about it online, so this is just personal experience. I heard older extended family using it, growing up on the West Coast in the 90's.
I have heard and used the term "public angel, private devil" in Australian English. It refers to someone with a personality who is overly concerned about their public image and so always seems happy and helpful to strangers and associates but at home they are sulky and sullen and difficult. They place a lot more value on the opinions of people who are outside of the family circle and much less on their close family and friends.
This is the opposite of what most people consider the norm ie. that you treat your close family and friends well and care less for strangers or what strangers think. At it's worst it describes a person who seems like a model citizen, doing charity work, lovable and heroic in public, while at home they subject their family to violence and abuse.
Because these people have such shallow relationships they can also be 'two faced'; especially with others that they know well. Instead of forming deeper bonds with people that they have known a long time they seem to become more and more contemptuous toward people that they know well. A classic sign of this personality type: they always seem to be more interested in their children's friends and partners than they are in their own children.