I was in much the same boat as you.
We had court paperwork that he was supposed to file, but it never occurred to me or my L to put in an end date.
Everytime I brought it up he said he didn't have the money, but he could afford to clothe and house his mistress (she didn't work).
I finally had to bit the bullet and pay for D myself. It took me about 8 months to save up the deposit. He has dragged the D on as well, so I've had to keep pouring money in.
I suggest looking in to see if there is free legal aid somewhere in your county. They can assist in filing the paperwork pro se. In the meantime, save those pennies. Turn in cans and bottles, and pinch pennies where you can.
Don't even try and make sense of what he is doing and not doing. It's senseless and you will end up driving yourself batshit crazy. Personally, it's my opinion that they delude themselves that 1) if they don't file for D that they can somehow come back home one day when they are done playing house with the HO, and 2) they can always blame us when Ho starts putting pressure on them to marry them. "I can't marry you because NikkiD won't ever let me go."
I am in a covenant M so my STBX literally cannot D me. He used this excuse with Shrek until I filed and had him served in front of her at their lurrrve nest!
Just do you and keep moving forward.