I went on a date with a guy and he lied to me and I'm still depressed. My best friend called me out for being weak. Am I?

Okay so about 3 weeks ago I want a date with this really cute guy. I didn't want to ask this because I was too depressed at the time. I thought he was a really great guy and we got to know each other but he end up lying to me and had a girlfriend all this time he was cheating on her. He only wanted to use me as his a second choice and I didn't want to believe it. My best friend was getting irritated with me for crying over him and it seemed like her niceness was about to go away. She scolded at me for being weak and crying over a guy that only wanted to use me to get though this desperate world. She said hostilly, "You're too blind to see what a cheater and a man white he is. You're being very weak! You're a strong woman and you need to get over it, suck it up and get on with your life! Let's go shop." She didn't even give me a hug. My other friend said, "Sometimes you gotta slap a hand rather than hold on to it." What does that mean?! Sorry if it was long. I've only known him for a month and he said he broke up with his ex. I though he was a great guy with a great personality but that was all a lie.