It is a disgraceful way for a prime minister behave. All MPs should vote against her deal. So write to yours and demand they do. This is what I have sent to mine, who happens to be Labour's Brexit spokesperson, Sir Keir Starmer:
Dear Sir Keir,
On 29 June, you promised me that Labour would oppose Theresa May's 'deal' unless it satisfied all six of Labour's tests. As it does not, I assume that you and every Labour MP will be voting against it.
If any Labour MPs decide to vote for it and throw a lifeline to this disgraceful 'government', I trust they will be expelled from the party. Such conduct would be inexcusable.
I also trust that if May's 'deal' is defeated, Labour will move IMMEDIATELY to meaningful action. The best course would be to revoke Article 50, and then leave Brexit-supporting MPs to get together to see if they can agree an approach to leaving the EU, while the rest of the country gets on with its life. If ever they do manage to agree anything, that could then be put before parliament, the government, and, if necessary, the people, to decide whether it is something that is worth proceeding with BEFORE it is put to the EU.
If Labour does not have the stomach for that, the next best option would be a referendum on May's deal or Remain, and if even that it is a step too far, I suppose you could try for a general election, though I do not see how you can win over enough Tory rebels to secure that.
By the way, did you see the latest YouGov poll in 'The Times'? https://twitter.com/SamCoatesTimes/status/1084786649014460416
In spite of their shambolic performance, it gives the Tories a 6 point lead over Labour. Backing Brexit isn't working! You need to change before it's too late.