Ooh, Cassie, I live in Kingston. Do you live here or nearby?
Pram, there's been lots if sensible advice here so I won't waffle on. My situation is pretty complicated (everything in my life is). DP has three children, a little girl who lives in another country (the result of a holiday fling when he worked in a holiday resort and had a different girlfriend every week) and six-month-old twins by his ex, who he hasn't seen yet though very much wants to. I wish this baby was his first. I hate the fact that two other women had his babies before me
Which makes me a hypocrite because I have two sons and he has to accept us as a package deal. Same for you, I'm afraid, DH and Oliver come as a package and you have to accept them both, no matter how hard it is. None if this situation is Oliver's fault. I'm sure he'd rather have his father live with him full time but he can never have that so don't begrudge him one day a week with DH. I agree that Oliver doesn't need to have his own room. Sharing with his father seems like the best option. DH could get Oliver involved in choosing things for their room so he feels comfortable when he stays.
Grey, congrats on the wedding 
Kara, 10 children!? Wow.