Should I get involved again?

I've been estranged from my now 32 year old son (he had knocked up two women at the same time, spent time in jail for car theft - I'd had it), for ten years now.  The last time I saw him or his oldest son, the son was four years old.  To keep down confusion I'm going to call these people wife A, wife B, and children 1,2,3,and 4.  When child 1 was 4, wife A was pregnant with child 2, and wife B conceived child 3 (they didn't marry for four or five more years).  At that point I had had it with his behavior and wrote him a letter telling him to find me when he got his life together. 

Since then wife A divorced him, took children 1 and 2 and disappeared.  I never met child 2, though spent lots of time with child 1 until he was about 3-1/2.  My son moved in with wife B and made child 4 with her about four years later.  So now I have a 14 year old grandson, a 10 year old grandson, a 10 year old granddaughter, and a 6 year old grandson, all of whom I have never met except for child 1.  My son has lived all this time about an hour away from me.   He got married about 3-4 years ago but I refused to go to the wedding, believing that would not be the appropriate way to reunite after so long. 

I've thought long and hard about drawing that line in the sand and if it was the right thing to do.  I've really been missing out on my grandchildren's growing up, and I do believe I would be a good influence - I mean, I'm a nice person and I have basically very good values, dont' drink or smoke, and have a stable second marriage.  I think we could be good for each other.

Now last week he turned up on Facebook and agreed to be a Facebook friend.   I saw wife A was a FB friend of his and wrote her a note and offered to befriend her.  Today she responded and accepted my friendship.  She also wrote a note saying that if we reestablish a relationship with children 1 and 2 she wants it to be consistent (which she never was when they were young) because the children  have been through so much and they don't need any more instability in their lives.  I can certainly be on board with that. 

Trouble is, in looking at her photos, I see the kind of life they are living, which looks - well - for want of a better phrase, trashy.  I've seen my own poverty stricken days but this looks more than just poverty, more like a lifestyle, the backwoods, yahoo, dirt driveway and yard, pieces of pickup trucks lying around, house filled with several unrelated adults and children, maybe - of course I don't know what the relationships are.  I don't know if she ever remarried, but she took back her maiden name.

I'm scared.  It's really early, here.  Do I really want to hook up with that kind of lifestyle again, which I managed to work my way out of and haven't lived associated with for years?  Could I be bringing on a heap of trouble?  Would the good of knowing my grandchildren 1 and 2 be worth the risk of taking this on? 

I could just let it lie - but then I'd never know, would I?  She's told them about me and says they are open to meeting me again.  The thing is, I know that if I did this it couldn't be just on my terms, on my turf.  I'd have to be willing to go be part of their lives.  That's what I'm afraid of. 

Any insight would be helpful here.  Sorry it's so long.  My son and children 2 and 3 is another story for another time, and not quite as difficult, I think.