I've ummmed and ah-ed about whether to post on this thread, as I am not a Catholic and have to admit that there is much about Catholicism that I just don't 'get'. You have been in my thoughts and prayers, though, and I thought I would share with you some things that were discussed in my bible study group yesterday which, coincidentally, was on the subject of divorce. If it is not helpful to you, please ignore it - the last thing I want to do is cause offence on top of what is already a desperately difficult situation for you.
For reference, we were looking at Mark 10: 1-16, where the Pharisees ask Jesus outright on his opinions about divorce.
Jesus response was (in summary) that there was God's divine law - that a man and a woman, once joined, should not be parted. However, Moses wrote a law that allowed for divorce 'because you are so hard to teach' (in some versions, the passage read 'because your hearts were hardened').
We've been working through Mark's gospel from the beginning and this idea of our hearts being hardened comes up again and again. God / Jesus over and over again make concessions to human weakness (our 'hard hearts' which make it difficult / impossible to follow God's divine law) acknowledging that we weak humans will never meet God's high standards, and so concessions to our sin are made.
Of course, the ultimate concession to this sin is Jesus' sacrifice on the cross. He died so that the effects of our sin could be erased - so that we could live freely. Sin must be avoided of course and we must always seek to live our lives as free from sin as we can manage - but through Jesus our sins, both past and future, are forgiven.
On this basis, I cannot see how the 'sin' of divorce, or even the sin of adultery, ought to preclude you from taking an active part in your faith and particularly in communion. In fact, if you were free from sin, you wouldn't need it, would you? It is because of our sins that we need Jesus. He came because of our sins, and because we were unable to live up to God's ideals. That is the whole point.
As I said, I really hope I am not speaking out of turn. I also hope and pray that you will find peace with your situation, whatever you decide.