Today I have re- tested the circuit, this time without the IR2110 and using arduino instead. I have programmed arduino to send two train pulses A and B, being B opposite to A, then a TC4468 to lift voltage from 5v to 12v and then the mosfets.
Knowing the value of the capacitor and primary of the transformer, the resonant freq. is 113kHz aprox, so I programmed pulses A and B to be this freq.
The circuit worked, it sends a nice waveform even when going for voltages of almost 50V (causing drain voltages of more than 140V),
the mosfets endured well (gates have lots of ringing but it's understandable, the circuit is just a test with long paths).
Everything I have said above means that the IR2110 is failing someway, because the capacitor-inductor-mosfet circuit works fine.