Fatal Madness

My first ever book I wrote three years ago. At some point, it was taken down by me because it had multiple grammar problems that needed to be fixed, but now it's official. Here is a description of the book:

"Long ago, Alex was relaxing in his chair, drinking a glass of whiskey and smoking weed along with his friend, dreaming big.
Things weren't so bad before, he had an average paid job, a nice custom chopper motorcycle, and a medium-sized apartment.
He used to spend money faster than a walk in the park on expensive drinks and drugs until one day...And that one day changed his whole life, from being a party boy to a drug dealer selling high-end drugs on different turfs owned by other gangs in the city for a living.
Some time later he met this girl, who turned out to be an assassin sent to kill him, but the hit turned out to be a huge failure. Now he got stuck with her to ride along, scared to death, on a long life trip to survival.
After some time he finds himself becoming a hitman, taking contracts and so earning more money than he ever hoped in his life thanks to this girl for showing him this hidden world, full of blood and madness, where even one dollar can decide your fate, life or death, although things never end well...Or do they?
They will have to find out after taking down the mafia and every gang... No mercy... It's just business. "