It sounds like you are having to make a choice that you don't want to make. Since you've been invited, why don't you go to the counseling session and see if you can talk about it there. It might help a lot to have an impersonal third party present.

Definitely don't move in together until you feel at peace. You are in the best possible position to get resolution. You'll lose some of that power when you live together.

Might I add that if what you want is marriage, don't settle for living together first?