Should I leave my girlfriend/ fiance' ?

I have been living with my girlfriend for almost 9 years. We met on a chat line when I was still married and admittedly cheating on my now ex wife. My divorce was finalized about 3 years ago. My girlfriend and I have been living together since 2 weeks after we met and for the 1st six years I was still married to my ex. MY heartache come from the fact that she has 2 children 17 and 19 years old. Her 19 year old son dropped out of school 5 years ago and has a drug addiction and refuses to pay room and board. I have a problem with this because I was raised by a single mother and payed room & board and have worked full time since I was 16 years old. I own a successful company and my income is about 150k per year (including housing benefits etc). so it's not a case of needing the money it;'s really the principal of supporting a soon to be 20 year old kid who has been looking for work for 6 years but due to his addiction and lack of education is unemployable. My girlfriend dropped a bomb on me last week when watchiing the television show 16 and pregnant and she told me "if any of my kids have children and can;t take care of them I wouls adopt them" - I didn;t say anything but internally I had a meltdown, I am 45 years old and supposed ot be enjoying life. On top of this my girlfriends 16 year old daughters friend had a baby she abandoned and the baby has been living at my home for the past 8 months. Essentially I am supporting my girlfriend (although in her benefit she has a small income of about 2000 per month). My life as I dream of it involves a small condo with a gust bedroom for the kids to visit. today I have 3 kids living with me that dropped out of school several years ago and contribute zero to the family bills and on top of that an infant baby. My girlfriend is a saint for taking in this baby. I give her credit but I was never once asked my opinion nor permission to have this baby live with us. There's alot ,ore to this story and there are 3 sides to every story as we all know. But I;m ready to pull the plug and just leave them all due to thier lack of consideration and respect. Also they have 3 dogs that have pretty much turned my house into a place that smeels like urine and feces 24/7. We live in a beautiful home but there are an average of 2-4 friends sleeping over every night without my permission and half the time without my knowledge. I world 50-60 hours per week and am really getting sick and tired of my house being the community center for everyone in the neighborhood that is uneducated , unemployed and hooked on drugs. I want out but don;t want to be that guy that left a single mom high and dry. Is this bad karma coming back to haunt me for my sins of 10 years ago? Or should I get the hell out ? Any comments or advise would be greatly appreciated/ Thanks !