On another thread you stated that your mom works at a job, taking home about 1600 dollars monthly after taxes. This doesn't indicate neglect... this is a working woman who apparently wants free time on the weekends and doesn't want to feel she must stay with her teenager during her off-hours. She apparently wants you to be more independent, at age fifteen, and less dependent. It reminds me of mother bears who at some point reject their children so they're forced to go out into the world to find their own way. Your mom must think you're ready.
At one time I homeschooled my kids and I know it can be lonely for children and teens. It is important that you have your own social life. How are you doing with that?
Criticizing her on morality issues isn't wise. You can't know exactly what she's doing when she's not with you, or what's going through her head. If she's been single for years, she's probably lonely for male companionship. This isn't as bad as you may think. And many adults choose to drink alcohol. If you don't like the things you believe she's doing, then don't do them in your own life. But recognize she has the right to live her life the way she wants to... and that she's still working to make a living which requires a level of responsibility she's capable of handling.
Calling this child neglect and calling the authorities probably wouldn't make your situation better. Children taken into foster care (and at this point you'd probably be in a group home) tend to lose a lot. They lose a lot of freedom, independence, their comfort, security, private home computer, friends, neighborhood, pets, opportunity to see relatives, phone privileges - all kinds of things! I don't recommend a call to CPS or child welfare services (whatever it is called in your state). Most teens that do this end up regretting it. Statistics have shown that children are ten times more likely to be abused in foster homes than in their natural family homes. See http://www.fightcps.com
for more information on that.
And besides, you're fifteen! I've known people who left home at fourteen and made it on their own.
So my recommendation is to detach from your mom and work on making your own life happier and more fulfilling.