Why MDMA? Don't you have access to drugs that are more reliable in ODs? Like Heroin and other opioids.
Btw the SSRI you are taking is blocking your serotonin transporter, the MDMA has to bind to it to enter the neuron and produce its effects on serotonin release (the main one) but it can't because of the medication you are on. That's why rolling on SSRIs is boring as hell.
What I am getting at is that your antidepressants could actually decrease MDMA's lethality rather than enhance it (a MAOI would surely do that, an SSRI? I don't know).
You could surely sedate yourself with benzos (again, they are used to treat stim ODs so...) but it doesn't mean they will keep you asleep or that the pain and phisical discomfort would be bearable (assuming the E would work at all).
My advice? Forget about this method, you're only going to hurt yourself. MDMA on its own is a relatively safe drug, you'd need to take A LOT to CTB. IMO all uppers ODs should be avoided. MDMA, Meth, amps, methylphenidate, MDPV, cathinones... maybe IV cocaine could be an exception (high letality) but I definetly wouldn't recommend that either.