Abh with provocation - possible sentence?

my son was in a relationship with a girl for over 4 years which went sour last year when she went off with his best friend! These two guys were like brothers so it was very hard on him, a double betrayal if you like as he lost two relationships. this girl however, has never let go of my son who worshipped her incidentally (and thats not just me being a mum - its true) since their separation she has phoned him whenever her life isnt working out for her and basically has not left him alone to pick up the pieces and move on. A few weeks back they met up and she slept with him saying she had split from his mate and led him to believe they would be starting over. He was elated as he is still in love with this girl. however the following week after receiving several calls from her to go round and see her, when he turned up she stood talking to him for about 10 minutes when he heard sing from behind a door only to find the so called ex boyfriend and ex mate in another room listening to the conversation. When he asked what was going on she simply shrugged and smiled! At which point my son (stupidly) then pushed past her and aulted him which has resulted in him being charged with ault Occasioning Actual Bodily Harm, (the lad was left with bruising to his face no broken bones or anything like that) He is in Court next week for this and he admits this ault. However the ex girlfriend claims my son aulted her in the process which he vehemently denies. His bail conditions are that he does not contact either of these persons involved and he had adhered to this HOWEVER she still rings my son, playing with his emotions and messing with his head and quite frankly i am worried to death that because he lashed out my son is going to face a prison sentence for snapping under duress because of the emotional hold this girl has on him. the police are coming to take a statement from him because this girl is contacting him when she should be leaving him alone. Can anyone please advise on the possible outcome of this situation? Do the courts take account of emotional factors when dealing with offences such as these? I.E provocation? Thankyou for taking the time to read such a detailed question but it needs to be detailed to get an informed answer....