Substantial amount of new responsibilities and overwhelm and pity

My mom just passed away and I am devastated as we were close. My dad is homebound and needs 24 hour care. My mom took care of him, as well as her 91 year old mom how lives alone. She did all work, gets his meds, paid all bills, all shopping, banking, cleaning, etc. for both. Now, a lot of this will fall on me. In addition to looking out for my niece. My mom helped her a lot as well, even though she is an adult (who doesn’t drive and is on mental disability). I do have help from family members, whom I have been calling on and will continue to do so. We are also looking into long term care. Some of it I really need to do, such as the banking, for security reasons. The next 2 weeks will be the busiest, as in addition to figuring everything out, I am also working on the administrative side of my mom’s death (certs, etc.). I am a professor, so after that I will be getting 5 weeks off…thank GOD! I am also single, so I need to take care of my own household.
However, there are moments when I just feel like there is no way to do all of this, and effectively do my own job and take care of my own home.

There are times when I feel so Overwhelmed, that I can’t do it and things will fall through. I am able to step back at times and tell myself, just day-by-day! I Got this! Yet, the shear amount of work seems too much!

I appreciate any help!