Feeling shitty after FWB date

I hate how horrible I feel after sleeping with this guy. He made it clear there's nothing more between us. He told me from day one that I shouldn't get attached. I always think I'll be able to handle it but then I feel horrible and cry afterwards. After we sleep together he's on his phone ignoring me and I just get up and go home. I'm trying to be a girl that can sleep with someone without a care but it's hard.