My girlfriend dumped me after I had drunken sex with my best friend’s married sister on his wedding day

DEAR DEIDRE: I HAVE been dumped by my girlfriend, disgusted my parents and lost my best friend after a drunken tryst with his sister on his ­wedding day. Last month was my best mate’s wedding. It was a massive, expensive event and I spent most of the night dancing with my girlfriend. I’m always the...