Lately I have been in love with a female coworker, but I have a girlfriend of 5 years and a 4-year-old with her.
I would you put your girlfriend through this?
I don't know whether she's OK with it or not.
You should not abandon your family for a coworker. You can destroy many lives and get fired from your job if you start a relationship with your coworker.
I'm going to kill my gf tomorrow. I already have my lovers outfit ready.
Based on that comment alone I know you're going through an extremely tough time mentally. You need to seek help immediately and get yourself into intake before you do something you're going to regret. Having this relationship with the coworker is causing these problems with you.