I believe that it would be wrong for you to not take communion because someone who is a "heretic" has partaken. That should not affect YOUR ability to receive the Sacrament correctly. Just ask your priest how he feels about you denying yourself the Eucharist when you are spiritually prepared (as much as us sinners can be!) to receive it.
Besides, you don't think this happens in every church where there are a number of people attending? You just are not aware of everyones beliefs.