Let's be blunt here, OP: your husband is a violent, aggressive, abusive, unpredictable drug addict. Being a drug addict doesn't mean being collapsed with a needle in your arm under a railway bridge, wearing rags. Your OH has all the hallmarks of serious drug addiction. Cannibis use, particularly if he is using the new types of skunk, can cause serious changes to brain chemistry, from anything from being a moody arsehole to full-blown psychosis.
Don't kid yourself that him being angry outside the home doesn't mean he isn't abusing you. That just means he abuses you and others. Do you know that being rude to waiting staff is a huge red flag in spotting an abuser? And that being violently angry with his own mother? Huge red flag too.
You cannot change him and you cannot help him. It is not your place to. When you are being abused this way, it makes you feel responsible for him, but you are not. What you ARE responsible for, however, is the welfare of your children. If you think they haven't witnessed any of this appalling behaviour, or, more importantly, aren't being affected by it, then you are more deluded about this than he is about the cannibis affecting him! Children see, hear, perceive and feel everything. Being in this atmosphere is guaranteeing them behavioural, personality and relationship problems for the rest of their lives. Abuse is acceptable in their family, be it screaming obscenties at Mummy or in the car. Treating women like shit and women taking the abuse is normal in their family. Treating strangers (other drivers, waiters, etc.) aggressively is normal. Taking drugs and addiction is normal (they will kow one day). Irrational behaviour is normal. Expecting other people to tolerate whatever vile behaviour you throw at them is normal. Allowing yourself to lose control of your temper and control is normal. Having no respect for anyone else is normal. Need I go on? Both their parents are teaching them to be future abusers and victims, and to be shitty, addiction-prone individuals who can't and won't treat others properly.
He sounds like an immature, abusive knobhead who believes he is entitled to indulge his own temper who also happens to be an addict partaking of a drug infamous for affecting temper and behaviour.