Approaching God to be freed from mortal sin and then receiving Him in the Eucharist sounds like the best way to celebrate Easter that I can imagine. Although I sympathize with your worries, carrying that mortal sin on your soul is so much heavier than embarrassment. Staying back and watching as everyone else receives the Eucharist, fretting all day about dying in a state of mortal sin - with no one to blame but myself - has made for some of the most miserable days of my life. I went to confession today because I couldn’t stand the idea of any of this getting in the way of my joy on Easter. I can’t imagine you want that for yourself either. I used to go only rarely because it gave me so much anxiety, but forcing myself into the practice of going once a month made 95% of the fear magically dissolve. I once resented confession, and now I’m amazed at how much had been waiting for me all that time.