Hate holidays...
Hello, this is the very first time I need to vent that much over a situation I got myself into while aware of the bad side of it.
I am 30 years old, have been a Professional living in a big city for the last 8 years and once I decided I had enough and moved back to my family in the country side. Then I met this extraordinary man and felt in love with him.. but he has 3 kids... and i'm not this type of person who is afraid of challenges. Even though I never really had the baby call in my life I felt it was ok to try and that life was bringing kids to me because I would have avoid it forever...
Anyway, it's been one year since I live a week on two with three awesome kids that are adorable and respect me. I feel really Lucky having this type of kids. Probably due to DH who is on my side and really caring about me.
Anyway, BM is really mad at him because he left her because she kept on bitching at him and she thought he would be back because he couldn't do any better than her anyway.. but she was wrong and she is really recentful at me, at him, at the whole world...
The worst part of all of this is holidays... BM keeps on avoiding the kids to stay alone with me. (I am probably seen as the devil or something) This is always end of the world if they stay 5 minutes with me.. but not during the holidays... then she is clearly happy to leave the kids with us nearly the whole time... Ruining my vacations is probably her favorite... So the Christmas week was our week. And usually on normal weeks, the kids sleep over her place wednesday or thursday because SS3 is too small to be mom less for such a long period. The sleep over night was obviously wednesday for her to have the kids on Christmas... so the day after (the 25th) we got them back and she will come back to take them on sunday as usual, but... she is on vacation today and this weekend.... and next week, she will bring the kids every single day for us to take care... because she works.. is it me or she could have kept them while she was on vacation!? Now, out of 1 week and half of vacation, I end up having 2 days for me... and the second day they are back at 4 o clock... while I know she is going to visit her friends this week-end... THIS KILLS ME! I cannot really tell that to DH, he is so happy having his kids over that much while he is home... damn it 
The same thing happened last summer while we all took our vacation during the same 2 weeks, I ended up taking care of the kids 12 days out of 15...
He takes care of them not
He takes care of them not you!
Simple.
Yes, you can say that to DH,
Yes, you can say that to DH, and you should. You aren't doing either one of you a favor by hiding the truth.
Marriage has, for centuries, been regarded as a contract; it's only been in modern times that "love" played a factor in who you married. Draw up your terms. You *chose* not to have kids thus far in your life. He *chose* to have kids, knowing the possibility of divorce existed and he would need to parent with or without a partner. Therefore, just as Raggles said, the responsibility of childcare is his not yours.
Tell your DH, lovingly, "You've been a father for X number of years. You are intimately familiar with the roles and responsibilities you have as a dad. I'm basically a 'new' mom and things that come easily for you and make you happy where parenting is concerned sometimes overwhelm me. I need more space than I'm getting right now. My vacation usually looks like ABC. Now, with the kids here everyday, it looks like XYZ. You can see how this is a big adjustment for me, right? I am excited to be part of this family, but I have needs that are not always going to mesh with yours, the kids' and BM's. If I'm put in this position regularly, I'm worried I'll become resentful over time. What can we do that gets you time with the kids (or whatever he wants) but takes a little parenting pressure off me?"
If he can respect where you are coming from, he respects you as a partner. If he gives you the "you knew I had kids and this is how it works when you're with someone who has kids" speech, or he calls you selfish or something of that nature, he sees you as a substitute mom and you're going to have problems.
I explained to my FDH that certain things come naturally and easily for me as a parental figure and I will do those things willingly every day. Certain things are inconvenient, unpleasant, or difficult for me to do as a parental figure, but I am willing to do them because they help him and I love him and want to support him. Then there are certain things I simply can't handle as a parental figure - things I probably couldn't deal with even if I was a bio-mom - and I just will not do them.
He doesn't always like the things I will or won't do, but I don't see how either of us (or my skids) can build a peaceful and happy(ish) relationship if I'm not completely (but lovingly!) honest about my strengths, weaknesses, and limitations.
What do you have to gain by not speaking up? He'll think you're okay with everything and feel totally content; you'll feel overwhelmed and resentful for X number of months/years before you tell him the truth and he'll feel totally blindsided when you do.