Meeting the kids in a new relationship after divorce

I need some input from anyone that wants to offer it.

Here's the layout:

I am 50yr M, was married 21 yrs, divorced was final 12/21/11. My new girlfriend is 55yrs, was married 25 years, divorce was final 5/5/11. We met in 07/11 (between the two "final" dates). I had a 16 yr old daughter & 14 yr old son. She had a 22 yr old son & 19 yr old son. (BTW, we both still have all of these children, now all 2 yrs older).

In the case off MY children, daughter left home to live with ex-wife about 15 miles away. Son stayed with me. MUCH dysfunction there as far as cross-communication. Daughter not really talking to me too much, very much aligned with her mother. Son having very little to do with his mom (my ex), partly because of his resentment that she left, partly because he thinks he's doing me some benefit, because ex & I are not on greatest of terms.

Girlfriend's children: Older one in Grad School, living with HER ex-husband about 60 miles away. Younger one living on-campus at college about 200 miles away. Both kids on speaking terms with her, although somewhat awkwardly (in HER mind) because they are under the impression (due to her ex-husband's doing) that the divorce was HER fault because she had an affair (which she did).

Both my kids have met my girlfriend. My daughter (now) has an "I don't care if you date, or who it is" attitude, has grown, and says as long as I'm happy with the girlfriend then all is good for everybody involved. My son likes my girlfriend, always has from the time he met her, probably because of a "when dad is happy, life is easier all around for everybody involved (he & I)" perception.

Now here's the rub:

My girlfriend's kids have been rather "put off" by their dad's dating (Internet-dating site women half his age, with younger children). Such to the point that they have told my girlfriend (their mom) things like "You're dating ? Good for you. Dad is too and we're forced to see it. We'don't want to hear about it - his dating OR yours".

She & I have been dating exclusively for 22 months. Neither of us dated anyone post-divorce prior to meeting each other. We get along wonderfully. But I have yet to meet her boys. She feels extremely guilty about "wrecking" her marriage (and their "family" life) and is just getting comfortable with having "less awkward - more normal" relationships with her sons. I am uncomfortable with these sets of relationships - namely the lack of one between her kids and me. Partly, (mostly) because for holidays, her birthday, and any special events--if one or both of her son's come into town, I am forced into the twilight zone. I understand it, but it's been nearly 2 years now. These are not little children, but young adults. She is letting their stated desires drive her actions when it comes to me, and I am frustrated about it.

Anybody have any similar experiences or words of advice ?

Thanks

I'm 49 and have been with my GF for a year and met her kids after about 2 months (they're 24 and 27) because my GF thought I was quite a nice person and wanted them to get to know me. This weekend my GF is coming to my place with her granddaughter. Clearly her kids have the right to their own opinions but does this mean that you can't for example see her at her place and stay the night? Because if that's the case then her kids are going to have an effect on your relationship. Ultimately if you don't like what's going on you will have to confront this issue. And if you avoid this you'll end up feeling more and more frustrated so it's not an issue you can avoid. Good luck.