ADD: My mom was a "serial dater" and put herself solidly first in family relationships - it bit her in the butt as her daughters hit adulthood. Dating with kids requires some respect of the kids part in the relationship. If you are willing to take the time, be laid back and positive about slow progress, it can work.
Original: Dad should look into family counseling so his son can deal with the pain of the divorce and the family's changing dynamics.
If you adore this man, you'll need to step back a bit and really buy into the fact that this is a package deal. Granted, the boy isn't a child, but he is your BF's child and will always be. BF is an individual and part of a unit at the same time.
Basically your new relationship is a kick in the face to the kid. The divorce is undeniably real now - dad is dating. He's jealous, yes, but he's also hurt and probably going through the feelings again because of this "proof" that it's over between his parents. It's another loss for him, and it's more concrete because he will actually lose time with his dad to some degree since you are starting to spend time together.
You have to decide if you are willing to deal with the baggage if this guy has "the one" potential. Then you have to move slowly - which is best anyway because the guy is reasonably newly divorced.
Do not look at this as a competition for affection or time. Do not have a "him or me" attitude. Do not get mad at this kid for being upset. He has every right. Don't push to meet the kid - two months is not long at all. Honestly, you really DON'T know the guy. You've hit it off, but it's super early on. Make sure YOU don't get jealous of THEIR time together.
DO let the man know that you understand that he needs to work this out with his son. DO give him the time and room to do it. If that means you guys meet for lunch instead of dating in the evening during his family time, then that may be necessary. DO encourage him to work with his son so they can find their footing.
I wish you luck. This is going to be complicated, so you have to realize that if you want to move forward with your BF.