Hey there sirixo, looks like you're new, so let met say welcome to the fold. You'll look back on your old life and wonder how you ever lived without Bluelight.
In short, no, this should not ruin your roll (MDMA), I would be very surprised if this has a noticeable effect on your experience. If you want an explanation:
SSRI's as they are commonly supplied, will end up stacking and more and more of the drug will be available in their body. You are not in this situation. I just felt it a good opportunity to mention that. A single dose shouldn't have a significant impact on all of your drugs, be they psychedelics, MDMD, whatever. I think it would be great if you could be mindful of the changes the Escitalopram (Lexapro) is making on you and your life and decide if these benefits outweigh the benefits of an occasional fun experience.
You might benefit from the SSRI and you might not, but the important thing is to figure out which is best. I previously mentioned the stacking effect of chronic dosing. This means that if you wanted to take a break from it, you would have to plan days or even weeks in advance. This would mean rapid and potentially uncomfortable withdrawal symptoms. I think if you stay on this relatively low dose, you should be able to make changes like this more easily.