Ummm...no...I think what was meant was, because the children are not your biological children, YOU do not appear to have the ties to them that would cause you to put them first - and you probably would if they were your own children.
Your resentment of them and the time your H spends with them would probably not be there if they were the biological children of the two of you together - because YOU would probably feel differently about the sitch. But because they aren't your biological children, and although you have made great sacrifices to raise them, you don't seem to feel bonded to them in the same way you might to your own biological children.
I've never resented my H for time he spent with our children - because they are an extension of us, and by caring for them, he is caring for me. That is a different dynamic than in a step-parent situation.
AS for your lack of friends - take a good look at this. I'm an introvert too, but I do have friends. Sometimes we introverts have to make more effort and move a little out of our comfort zone to make that happen, but the risk of putting all your eggs in one R basket is pretty severe.
