I'm going to consume edibles I got for my friend
Did you both agree that these were for your friend?
We agreed that we would share it.
It is understandable that you want something yummy but you shouldn't eat things that you are meant to share. Your friend will think that you are selfish.
I'm going to buy some more.
It's good that you are planning on buying more, so that your friend will not be deprived.  However, you might not be able to get them in time, as the store could be sold out or other things could get in the way.  As much as you want to indulge, I think you should at least leave your friend's half alone for now.