You could vote Lib Dem and we still get Brexit. Whether someone votes Lib Dem or Labour, there would be a second referendum. I am a remainer and if we do have a second referendum, I would vote remain again. Having said that, in a GE I would vote Labour because they have quite a comprehensive policy platform outside of Brexit that I happen to agree with... whereas, do the Lib Dems actually have any other policies?
Also, it's pretty untrue that any form of Brexit would be a disaster for the UK and especially the poor. Even though I would much prefer to remain, Labour would still invest significantly whether there is a soft Brexit or no Brexit. I am talking large investment in house building, infrastructure, green energy, education, public services. That would go ahead regardless.
In my opinion, the poor people in this country would be significantly better off under a Labour Government with a soft Brexit, than a Lib Dem Government with no Brexit at all.