The answer is: simply stay in your pew and make a spiritual communion and resolve to go to confession asap.
As an aside, if you see someone staying in the pews, you do not know if they are:
- Non-Catholic and respecting the Church’s law about who can receive Communion
- Someone who missed the required fast before receiving
- Someone who has already received twice that day
- Someone who is not spiritually disposed to receive (serious sin, married outside the church, divorced and remarried without an annulment, left the Church for another denomination, etc…)
I say this because we can automatically presume that people in the pews are in serious sin. That is not so, and it should not be something that we worry people are presuming on us if we refrain from going up. It is a private matter between you and God and no one should be coming up to you to ask why (unless it’s your confessor).