Gain margin and Phase margin can be found from the bode plots generated by ltspice and by using the cursors.
Phase margins can be found when the gain is at 0dB and Gain margins can be found when the phase is at -180 degrees.
The phase margins I found by inspection were at 2.61Hz with a phase of -91.9 degrees, and 24.37kHz with a phase of -347.1 degrees.
Therefore, the phase margins are Pm = 180 + P = 88.1 degrees and -167.1 degrees.
The gain margin is 504.63Hz when the phase is at -180 degrees which correspond to a gain of 29.7dB.
Therefore, the gain margin is Gm = 0 - G dB = -29.7dB.
Thus it can be concluded that the system is not stable as the gain and phase margin are both negative (Gm is greater than 1).
I would highly suggest performing a mathematical analysis of the circuit to produce a transfer function and thus other methods can be used such as root locus, Nyquist plots or routh-hurwitz tables.
Anyone please correct me if my conclusion is wrong. I'd normally find stability through analytical methods.
EDIT: My conclusion was wrong, oops