Hello and Best Regards BwannaWill,
I think you are being responsible in taking time to play this all out in your mind. I respect you for that. You are making a hard decision but I would definitely include family if you have the option to do so. It will mean a lot to both you and your son. I also think your son to be the most important thing to consider as your GF will be getting the help she needs. Hopefully, down the road it will put you all on better footing for the future. I commend you on coming up to the plate. Do what you need to do for the two of you.