Everyone deals with things differently.
Your Mom is scared and she's trying to cling to you.
The real fact of the matter is that you may have to give up some of your hours as she progresses in her treatments because she may need you to drive her to the doctor or for another appointment. If she's like my sister, she will feel so sick that she'll want to stay in bed on her very sick days, by herself, sleeping and waking to be sick. You'll have to keep an eye on her to make sure that she doesn't dehydrate. If she does, she'll need fluids and you'll need to get her to her oncologist's care. There were 2 times that my sister couldn't walk into the treatment center. She had to use a wheelchair. She walked out though, once she had fluid in her again.
My sister is finally finished with her treatments. She has a schedule of people who help her during the week. My day is Wednesday. I take her kids and we hang out at my house, we go to the library or do other fun things. They are 3 and 6 and love to play Wii bowling with my kids. She said that she's more scared now because she is waiting for the PET scan to be scheduled to see what the chemo and radiation accomplished. But, I may be able to take her to my club to go swimming soon with her kids because she'll probably feel up to it. I also make dinner each week to give her DH a break. No one else has decided to follow my lead, but they appreciate my meals every week.
Does your Mom have sisters or friends who could sit with her sometimes so she's not alone so you can go to work or on a date? You have the best tester for a boyfriend right now. If, after you get to know him a little better, he doesn't want to hang out at your house so you can help your Mom, he's not a guy you want to have a long-term relationship with anyway. Maybe you could play that card with your Mom.
The other suggestions that have been made are great. Talk to her social worker or doctor about a therapist for both of you, even for your Dad, too. That can help to keep everything in perspective. This is new to your whole family. Adjustments need to be made that a counselor can help you to ease into.
Prayers for your Mom and for Pakey.