I will address 3 issues: 1) whether going out of status will affect your pending I-485 application, 2) whether you accrue unlawful presence if you go out of status while I-485 is pending, and 3) whether you are deportable if you go out of status while I-485 is pending.
In most categories, in order to be eligible for Adjustment of Status (I-485), you need to be in status at the time of filing I-485 (see USCIS Policy Manual, Volume 7, Part B, Chapter 3), and have never been out of status in the past (see USCIS Policy Manual, Volume 7, Part B, Chapter 4). Even for those restrictions, however, going out of status after the I-485 is filed will not by itself affect the I-485. See USCIS Policy Manual, Volume 7, Part B, Chapter 4, section G:
For purposes of the bars to adjustment, a nonimmigrant only needs to
maintain his or her nonimmigrant status until the time he or she
properly files an adjustment application with USCIS so long as the
nonimmigrant does not engage in any unauthorized employment after
filing the adjustment application.
You may have noticed if you went to the above pages, that those bars to adjustment do not apply to "immediate relatives". You are in the Immediate Relative category (spouse, parent, or unmarried under-21 child of US citizen), and you thus don't even need to be in status at the time of filing I-485. In other words, you could have stopped going to school years ago, and still be eligible to file I-130 and I-485 now. This is summarized in USCIS Policy Manual, Volume 7, Part B, Chapter 8, section B:
Certain adjustment bars do not apply to an immediate relative,
including the spouse or child (unmarried and under 21 years old) of a
U.S. citizen, and the parent of a U.S. citizen older than 21.
An adjustment applicant applying as an immediate relative may be
eligible to adjust status even if:
- The applicant is now employed or has ever been employed in the United States without authorization;
- The applicant is not in lawful immigration status on the date he or she files the adjustment application;
- The applicant has ever failed to continuously maintain a lawful status since entry into the United States;
- The applicant was last admitted to Guam or the Commonwealth of the Northern Mariana Islands (CNMI) as a visitor under the Guam or CNMI
Visa Waiver Program and is not a Canadian citizen;
- The applicant was last admitted to the United States as a nonimmigrant visitor without a visa under the Visa Waiver Program; or
- The applicant has ever violated the terms of his or her nonimmigrant status.
You do not accrue "unlawful presence" while your Adjustment of Status (I-485) application is pending. So even if your I-485 is denied or abandoned, you would not have accrued "unlawful presence" for the purposes of determining whether you trigger a 3/10-year ban if you leave the US. (Although in your case it doesn't make a difference anyway, since F1 students are admitted with "D/S" on their I-94s, so do not automatically start accruing unlawful presence absent an application denial or immigration court decision.) See USCIS Adjudicator's Field Manual chapter 40.9.2(b)(3)(A) (on page 85 of this PDF):
(3) Aliens Present in Unlawful Status Who Do not Accrue Unlawful
Presence by Virtue of USCIS Policy for Purposes of Sections
212(a)(9)(B) and (C)(i)(I) of the Act
(A) Aliens with Properly Filed Pending Applications for Adjustment of
Status or Registry ( Sections 209 , 245 , and 245(i) of the Act,
sections 202 of P ublic Law 99-603 (Cuban-Haitian Adjustment), section
202(b) of NACARA, section 902 of HRIFA, and aliens with properly
filed, pending Registry applications under section 249 of the Act)
Accrual of unlawful presence stops on the date the application is
properly filed pursuant to 8 CFR 103 and the regulatory filing
requirements governing the particular type of benefit sought. Note
that, if the application is properly filed according to the regulatory
requirements, the applicant will not accrue unlawful presence, even if
it is ultimately determined that the applicant was not eligible for
the benefit in the first place. The accrual of unlawful presence is
tolled until the application is denied.
As for whether you are deportable, it is generally said that people are not deportable just for being out of status while they have a pending Adjustment of Status application. However, I can't find this written anywhere in any statute or official rule, manual, or webpage. I believe it is a de facto policy that is followed in practice, but ICE always theoretically has the power to initiate deportation proceedings against you. However, Adjustment of Status is a defense in removal proceedings. So, in the highly unlikely case that you are put into removal proceedings, you can simply file a new Adjustment of Status application with the immigration judge, or continue your previously-filed-with-USCIS Adjustment of Status application with the immigration judge. The immigration judge has the power to adjudicate and, if warranted, approve your Adjustment of Status and close the removal proceedings. Alternately, the immigration judge can close the removal proceedings to let you file Adjustment of Status with USCIS again.