And if not, please, TALK to someone in your family about this! Yes, they may be reeling from losing someone themselves, but no one who loves you wants you to suffer.
Holidays are hard. Remember what this holiday and the family gathering are about.
What do you think will be more important for your family tomorrow?
That you are there? Or that they have cheesecake and fruit delivered?
If they only wanted food, they could have ordered out. That's not what this is about.
Forget the desserts. You will be forgiven. If you really feel badly, stop at a donut shop on the way there and pick up some donut holes. Then, when you have a spare second later this weekend, with no pressure, you and Marc can bake the cheesecake and deliver it to a local shelter or nursing home. Keep some of the fruit and donate the rest, too.
And about Fri....if you wouldn't be home, and Gabe is still interested in his son, let them have the time together. Should he have run it past you first? Of course. Email him that: "It is good to see you wanting to spend some extra time with Marc; he needs his dad. Just please let me know when you find those opportunities before asking Marc, though, so we can avoid disappointing him - I would hate to have to say no because of prior plans that you aren't aware of." Also, with Christmas coming up, you can plant the seeds for gifts: "Marc has been looking for some new clothes for school, so I thought I would give you his sizes before you went shopping, if you would like to get some for him for the holidays. He wears size X and X, and loves ____ and _____. He always loves your gifts." Who knows? Maybe they will have a guy's shopping trip.