Struggling with Step parenting

[cookiemonsta]

My DSS lives full time with us -his mother died before I met my DH :-(. We have been together 9 years and he is almost 14. I am really struggling at the moment. I feel that my DH and his family really favour DSS over our own 2 DDs.
Our 2 DDs are 5 and 3. My DH is taking DSS away to Thailand for the second time this year to visit relatives in October and his aunty is taking him to Ireland in a couple of weeks. I feel he gets preferential treatment. No one ever offers to take my 2 anywhere.
My DH is basically threatening divorce because he says I am being unreasonable and that I treat DSS badly and talk down to him. I just get fed up with him being on the xbox for 6 hrs a day and not giving anything to the family unit then being given loads of treats that the DDs dont get.
We are really struggling financially, but DH is happy to buy new phones, computers, trendy labels etc for DSS and I find myself buying second hand for my 2 dds.
Help me. am I being crazy? Do I just let this marriage fall apart? Is it worth saving or am I better off with my 2 dds on my own?
Sorry really needed to let of steam

You don't seem much of a family. Where are you going on holiday?
How do the 3 DCs get on together? How much do you do alone with DSS? How much does DH do alone with DDs.
Do you have equal control of the finances?

It depends on whether you think it worth saving. Generally the problem is that the older DSC is the second class member of the family but here it is the other two. You have a family of 5 and yet it doesn't appear to be that way.

I would sit him down and discuss it. Why is he not taking you all to Thailand? ( the Aunty taking him to Ireland is fair enough at his age).

If he isn't willing to change I would think you are better off without him.