Okay, myheart goes out to you because it is hard to hear hurtful things from our kids (or anyone)!! I have been there. My four year old just recently told me he hates me and I have no idea where he would have heard that either.

Just keep reminding yourself that they are saying it to get a rise out of you but that they realy don't mean it. Until they are older and DO mean it for the time being. Know in your heart that you are a wonderful mama and do what is best for your children and lvoe them with all your heart.
I have several different approaches depending on my mood, the child's mood, how much energy I have and where we are. Sometimes its best to ignore it all together if its a full blown tantrum. I then talk to ds later to tell him it's okay to have the feelings but not to say hurtful things. I tell him what he said that hurt my feelings so that he knows exactly what I am talking about. Then I give him examples of how to say what his feelings are such as "I am really angry that I can't watch 5 movies right now" instead of "I hate you". I tell them (I have three ds's) that they will still get their feelings out and across to me that way.
Sometimes sayign their feelings at the time of upset helps "I hear that you are really sad/angry/etc". Sometimes it helps to turn it into something funny "you sound so angry you could run faster than a heard of elephants!!" or I get out my magic wand and do what ever comes to mind with it. They usually join in with this one and start having fun or just talking about things. It can be really outrages or just putting their wishes into words. "It sounds as though I need to pull out my magic wand. I'm going to wave it in the air and from the sounds of your anger I need to turn myself into a frog. Ribbit. Once I'm a frog how am I going to hold my magic wand? Oh, you'll need to pick it up. I'll be trying to ask you to turn me back itno Mommy, but you're so mad, you might use it to send me to the swamp! Then what will you do, fill the van with candy?" Or, "with my magic wand, I could put all the money in the bank we would ever need, then daddy could stay home with us everyday. When we got tired of staying at home together our magic wand could take us to the beach." YOu get the idea.
Good luck and give yourself a hug!