being daddy

I have been dating a guy now for a little over 4 1/2 months. He was my best friend and honestly still is. He is the best guy I have ever dated (sadly to say)
Last night he got up set with me and I got irritate with him.
I am having issues with my son. He is 7. in 2nd grade. He is disobedient, talks back , and is disrespectful at time. I do the best I can as a single mom but I feel like nothing I do is good enough.
well last night my son was getting ready for bed.. had his snack and then asked for more.. i told him he could have an apple and something to drink... he threw a fet.. he didnt like apples. I told him that it was apple or nothing... so he took the apple and then asked me to peel it and cutt it for him. I told him no. up till that day he never needed it like that and that I was busy getting his sister to bed and he needed to get to bed too. he threw a fit.. went to his room and started screaming for me to cut his apple. i went and closed his door... this made things worse. i got his sister into bed... and his screaming continued.. i went into his room and told him that he wasnt going to get it cut and if he didnt stop screaming and acting a fool i was going to take the apple and close his door... at this time my boyfriend comes and starts yelling at my son also. we leave the room... and a few minutes later.. the screaming continues well it never stopped... and i again try and talk to him.. and teh bf comes in and starts yell... this time i am very irritated... we leave the room and i tell him that my son doesnt need both of us in there yelling at him at the same time.. i can handle it, i am in charge.
he gets mad and goes outside for a cigarrette..
i finally get some son to settle down and go to sleep.
the bf barely says anything to me for the rest of the night and goes to bed early with out me.
this has been something that has been happening for the past few week... my bf acts on emotion.. reacts in anger towards me son... and I believe over punishes.. (sentences, takign things away, grounding to room etc.) My boyfriend isnt there everyday... and I am the one who has to full the punishment... which isnt a big deal.. but when its something i feel is overwhelming... like multiple punishments for little things... it irriates me some...
we have talked about this and he has even admited that he does go over board with things... and he doesnt think i handle my children the way i should.. i need to be harder on my son (even tho i am told by other people that i am too hard on him) and that his mom was hard on him.. disaplined in , grounded, yelled, spanked, etc... and yea hes a decent person now... but it took this long for the point to get across... so is that way of disaplining the "right" way.