My boss has issues with me, on a number of occasions he has singled me out from the rest of the team and made comments about me to other team members like 'if she doesnt buck up shes out by January'
His lastest is an email he has sent to another manager who has asked for help with some work, he is based in another office and would mean travelling across the country, my bass has volunteered me to help, i said yes no problem as long as i have prior knowledge of the travel so i can make childcare arrangements
However in his email to this manager ( of which i was not copied in) he says 'Vinegar will struggle to commute (she is a single mum) so the work will have to be done remotely from here'
i am furious! how dare he label me and use my single parent status as an excuse 
i have never said i would struggle to commute and find his comment unprofessional, inapropriate and bordering on discrimination
what can i do about ?
the other manager has replied to his email and copied me and the big boss in on it, which is why i have come across it
i need to know how to deal with this, im so angry i cannot look at him