DEAR ABBY: I’m divorced. My ex-husband has a girlfriend and has just gotten engaged. We have two sons, 23 and 20, and they are going to their father’s wedding in four months. I’m kind of annoyed that they are going, and I’m not sure what an impact this will have on my life as the “ex” or how my boys will feel. Advice? — NEW ERA IN NEW JERSEY DEAR NEW ERA: If it isn’t too late, refrain from conveying to your sons your annoyance that they will attend their father’s wedding. They belong there. Give them the chance to get to know the woman without trying to influence them either way. Remember, ab…