Usually group work assignments have some facility to note who did what and highlight if there were issues of non-engagement from others in the group. Also you can and should just flag it to the module leader/tutor at the earliest opportunity anyway. It sounds like you've left it a little late which while understandable from the perspective of conflict avoidance probably makes things a bit trickier to resolve as there will be fewer ways to do so.
In any event I'd suggest you and the other person doing all the work email the module leader and highlight the issues and otherwise carry on doing the best you can so at least you can stand by your own work within the overall group project.