im so sorry your going through this
sending hugs your way. well first of all tell the so called friend to leave you and your husband alone. and i also think you should go and see someone but i do think you should both go, if your husband says no then he cant really want to make things work, if he is truely sorry and wants to show you how much he loves you he will go with you and after all it was he who betrayed YOU so he needs to talk about the reason he strayed so you can both work on it never happening again , if you dont get to the root of the problem how can you mend? how did you find out about them being together if you dont mind me asking? i guess you are also upset that he told you it was over but then carried on with her behind your back? so its not just him cheating its the lieing too you need to sort out. like its been said go see someone talk to them together, then and only then when you feel strong and have a clear mind think about how you feel and what YOU want.