I don't want to talk to my boyfriend after sex
Is there a reason that you avoid talking to him?
It's too exhausting for me.
Well, wanting to sleep after sex is totally normal.  I think he should be fine with it, and there' no reason to make a big deal about it.
I feel so bad about it though, I know he wants to talk.
I think that if you are tired after the act, there is no reason not to go to sleep. I think that is what a lot of people do when they are done.