CapricaSix, that's a really uplifting story - and it's an important point to make, that it worked out for the best for you AND your ex . I do know of relationships with a large age difference that have worked - one of my schoolfriends married a man of 53 when she was 19 - and they stayed happily together until she suddenly died last year at age 49 - which was something she never envisaged. She used to say that her only regret about being with a man so much older, was that she expected to be widowed young. Life's sadly ironic sometimes . Her husband is nearly 80 now and very feeble, but they had two lovely children who take care of him.
However, I have another friend, an exbf of mine, who at the age of 50 married his GF of 27 (a rushed holiday romance). He does have some annoying habits, but we all still thought it a bit harsh when she left him two weeks after their son was born.
I think it's hard enough to maintain a good relationship with a man your own age, but a very large age difference brings added complications - you have different cultural references (He remembers Andy Pandy, you remember Pingu ) - you may like totally different music, find different things funny, have different plans for the future - his libido may be fading (she says, looking sadly at DP) - and most of all, it's hard not to fall into a father/daughter role, with him making decisions that should be shared, or being critical of you and your behaviour, values and needs. Men can get very rigid in their ways. I sometimes think an age diff can work better when the MAN is younger, because women tend to be much more flexible and open to new experiences (well, I am, anyway ).
What Caprica said about her housing predicament is valuable. It's possible that you might be able to get temporary housing from the Council if you can prove that you are going to be unintentionally homeless - it might be worth contacting Shelter or your council's temporary housing team to find out whether this might be an option, given your situation in that you are living in his house and have nowhere you could go.
And wherever you go, I do think it's strange that he says he won't see DS. It won't at all be the same as the current arrangement. And how could he bear NOT to see his son? But if he continues to say this, please try not to cry. Remember, it's his choice, and his loss.
I really think you would find living on your own amazing - but you will need to have friends and support when you are on your own, so that you have FUN. So in the short term, while you are doing your homework on finding housing, checking on what benefits you can get, possible childcare, work etc,try to build some new friendships with other young mums. Find a toddler group, as ML suggests, see if your local library has a baby reading or singing group. Steel yourself to go back into the fray re finding housing - there are SOME landlords who'll take housing benefit tenants, but it takes persistence.
Remember you are a bright, intelligent, lovely person. Empower yourself and build up your self-confidence. At the moment, reading your last post, it sounds like he is subtly controlling. He is even trying to control your trial separation by saying he doesn't know how long it will last (probably because he fears it may last forever - he wants to call the shots to prevent that, by making you fear losing him). Remember, this is something YOU want, don't let him dictate terms.
Next time you discuss this, try NOT to break down. If he says you should have a break from each other, try agreeing calmly, and stating that YOU will be leaving. He'll be shit scared, but that is HIS reaction, HIS feeling. Something I learned recently at an assertiveness class at work, was that we are all responsible for our own feelings, our own needs. We are not responsible for someone else's (apart from our children, of course ). It sounds harsh, but it means that you need to think about YOUR needs and how to achieve them, and not worry too much about how needy he is (he may actually be needier than you are - which is why he is finding subltle ways to keep you under his control). He is responsible for his own needs. If his needs include you, then it is up to HIM to find a way to meet you half way so that you can both be happy. If he does not do that, it is not up to you to make it better. You can only do what feels right to you.
I think I'm rambling a bit now - not sure if I've phrased this post at all well, but hope you'll see what I mean. It sounds a bit selfish, but actually it's not. It's a way of thinking that empowers people and makes them truly adult towards each other - and it really works! Actually, why not get a book on being self assertive? It will pay dividends!