Seasider - as a bereavement counsellor I have just come home after seeing three clients, each one of whom is facing Christmas without a significant other, and two of whom will also be completely alone. I think that may help you to gain some perspective on your situation.
I think also you might want to reflect on the fact that you invited stepson and girlfriend to move back into your house for a pittance of a rent to enable their house-buying aspirations to be realised. That action has clearly been interpreted as one that shows you have been willing to place their needs before yours, and now they are doing exactly the same, so my advise is the same as Maremia's - be in charge of your own plans and don't perpetuate the idea that you are happy to be second best otherwise you will always be at the end of the queue.
Good Morning Good Friday 29th March 2024