So lost??

I want to apologize in advance, my thoughts might skip around a lot as I write this. I really don't know where to begin. The best way to explain my situation is, I feel like a robot the majority of the time. I am numb. I grew up in a big loving family, my mom and dad did everything they could to provide. My siblings were always there for me. We are a pretty normal family. As I got older I realized something strange, I felt no love. I can't say "I love you" to my family without feeling weird or unsure. I try and avoid saying it , and I only say it to my parents to make them happy. But deep down I don't really know what love is. In terms of relationships, I've had dozens of significant others in my life. None last, I meet a girl and I like her a lot at first, but quickly I lose interest. My most recent relationship lasted nearly 1,5 years, I never told her I loved her. I've cheated on her multiple times, and felt no guilt nor shame. This girl literally would do anything for me. She loved me even though I told her I don't have feelings like normal people do and I don't feel love. Some would say she's the most perfect type of girl a guy could ask for but I don't love her . I don't know why. I find myself only thinking about myself and my own self needs, but I come off as a type of guy that most people really like. I have a lot of friends, I was always "popular" growing up.. whatever that means lol. But deep down I know I never really cared about other people, but at the same time I really feel for people when it comes to their person issues. the only thing I've ever wanted in life was to be truly happy but I can honestly say I don't know what that feels like. I forgot to mention, I'm 22 years old and I'm a college student. I barely sleep at night, maybe 3-4 hours at the most, or sometimes I just don't sleep at all. Although I feel as if my emotions are really dull I am so afraid of failure that I've developed bad anxiety. My anxiety keeps me up at night. But I feel all of this has to do with my own desire for self fulfimnet versus caring about others. Also I go out and party usually 3-4 days a week, and very recently I've starting doing multiple drugs like coke, pain killers, and molly on the weekends. When I drink and do drugs, I feel like I can emotionally connect with people. I am afraid I'm developing a bad habit. I feel like I am a terrible person, when I was younger I actually cared about people but the older I got the more numb I have become. I've cheated on girlfriends and felt no remorse, watched countless people walk out of my life and not even care. What is wrong with me? I'm just really venting here it's nice to get it out, it's hard to talk to people who care about me. How do I tell someone who loves me "yeah I really don't care about you, I really just care about myself but I'm so fake and I come across like I care but I'm just in it for my own self interests" i hope that the way I wrote this is easy to understand, Im exhausted as I'm writing this right now, any input is much appreciated.

Just want to add more to my relationships. No one really knows I'm like this. most people see me as a very out going, fun loving guy.. In reality I don't really know how to act, I often find myself studying the ways others act and try and copy it because I feel like I don't know what the norm is lol it's really hard for me to connect with people on a deeper level. I am not saying I don't have feelings, I think I do have feelings but most of my feelings are dulled down and mainly for self fulfillment.. when I was younger, I think I really cared about other people. I was always there for my friends and listened to their problems and tried to help them. But I NEVER shared my personal feelings with anyone, I've always bottled things up. Never talked to my family about my issues, I just dealt with them myself. Over the years this made me just feel so numb inside like I said above, like a robot. I still don't tell people my problems or what's going on in my head, this is why I chose to write about this anonymously on this website. I've always depicted myself to be very strong and independent, this caused me to always act like I had no issues. I guess over the years it has caused me to hide all my emotions away, and now today I'm an empty vessel living it day by day like the robot I am