Following on from @AnneTwackie & @flirtygirl, & to take a more balanced view (on my part) in this spat & the future of the family in general.
So you are going through IVF, an emotional rollercoaster journey if ever there was one. All the emotions tangled up from the earliest part of your fertility journey through the gruelling processes & then the waiting - very challenging for anyone. Are you DF & SM aware of this? Are they supportive of you?
Again, I ask you to reflect upon your attitudes & behaviours.
No matter the emotional undercurrents of the years passed, the missed opportunities to bond with your father, SM & their children, no matter the seeds of your resentments, these matters are moot.
Because you as an adult have clearly hurt the feelings of another person, & you alone are responsible for putting this incident right by apologising. Whether the comment was deliberate, planned or off the cuff, you delivered the blow. It has been made clear that an apology from you would be accepted (therefore more than meeting you halfway) but you have declined this peace offering.
I expect that your DF & SM are in accord about not having you to stay in their home with your disruptive attitude & behaviours, & the compromise is the terms offered by your DH.
You could see this as the silver lining that you can have 1:1 time with your Dad. For a while this may work for you to salve some of your historic hurt, but it will run on how available & willing you both can be.
Bear in mind that both your DF & DM would have determined who you would holiday with & when during your teen years, NOT your SM. You mention money was short, so camping en famille was the default holiday with toddlers. Not much fun for a mid-late teen & odds are very little time for you & your dad, also not practical on the tent front - it would have been super smart to invite you or offer a short trip for you & Dad at another time, but people are fallible.
Please reflect upon on how a child’s perspective of events is not an absolute truth, & adults do this as well. For we all interpret events & motives by first impressions & experience teaches us to fact find, consider evidence & varying viewpoints before we land on a conclusion & take a fixed stance.
I ask you to reflect now as you are wholeheartedly bringing a child in to the world, & what you know as the facts of this will not be what people, & possibly your own child in due course, will see.