Well I'd get yourself down to CAB to see if they can offer practical advice in relation to the housing situation and I'd tell your ex that this is inappropriate and if they wish to spend time together they must do it at the new boyfriends house.
Being gay is not a phase and he will not get over this. You will have to learn to accept that. It will be better for little spotty to have two happy but apart parents than ones that stay together for the him.
I'm stunned you appear to be so unsure about it all?
If he was having an affair with a woman and wanted to move her in would you be in a quandary then too? Because at the end of the day that's what he's having, an affair.
Tell him to move out and have his "special nights" elsewhere!
cant stop crying knowing its never goin to be the same, baby spots wont understand will he? think i`ll take him away and sell the house back to mr chops as feel ill