Sorry if this comes across as harsh, but I have a hard time feeling sorry for you.

First, man up and do whatever she asks/needs of you when it comes to your son. Do not mess up, "forget", refuse to do things just because she's (rightfully) upset with you. And don't just do it because you want to get back with her one day, do it because he's your son.

Second, other than than what is required in regards to your son, stay away from her. Don't text her, don't call her, don't push her, don't ask her out on a "date". Just leave it alone. You caused this woman an awful lot of pain and anguish. The fact that you are thinking more about how to eventually get back together with her, rather than being remorseful over how badly you must have hurt her, tells me you just don't get it.

Third, if you have had any unprotected sex in the last 8 years, then get yourself tested for everything. A penile swab is a great way to teach yourself a painful lesson that screwing around is a bad thing.

Fourth, get some help. Find a therapist, a psychologist, whatever it takes. There is something causing you to act this way, and you are going to need professional help to figure out what it is, and correct that behavior. Do not expect an overnight fix, or to be "better" after 2 or 3 visists. It could take months of behavioral therapy to change the way you "think". You're going to really need to be commited to becoming a better person. If you don't have the fortitude to do this, then you're doomed to failure.