Im confused

There is this guy who I lost my virginty with few weeks ago he said he was single and so do I.no relationship we are just friends but we did it anyway.i got drunk and contact his ex girlfriend and ask her if they are still toghter then she said yes.and why I'm asking so the guy call me and ask why I'm asking people about him and stuff like that I knw I have messed up by sneaking around.i told him that he lied to me that he is single and he said my ex is crazy she needs mental help.what is that mean?.for some reason I'm disappointed at myself right now