Welcome, you are correct in some areas. Yes it is God who forgives our sins. Only God has that inherent authority to do so. However as we see in the Scriptures, Jesus, who is the Second person of the Trinity gave that authority to the Apostles, and they through Apostolic Succession transmitted that authority down to their successors, who are the bishops and priests who serve the Church today.
One thing that many Catholics and non-Catholics do not understand about the Sacraments, is that they are all means which Jesus uses to give us grace. While He did establish some criteria, such as water for Baptism, and Bread and Wine for the Eucharist, which we must use for the sacrament to be valid, we sometimes forget, it is not the priest’s power or holiness that makes the Sacrament work, but that they have been intrusted with Jesus’ priesthood. It is Jesus who promised that when the Apostles (and today the priests who share in Jesus’ priesthood today) forgive sins, it is Jesus who is working through the Sacrament. The priest is acting on His behalf, (in theology we call it In Persona Christi, or in the person of Christ) the same way the president of the US or the Queen of England send a delegate to another country with the authority to speak on behalf of the one who sent them.
As to your marriages, Jon is 100% correct, you need to speak to your parish priest. Now you can go to a priest at any parish, and discuss the marriages. Depending on the situation the marriages may have been perfectly legal in the State or Province you lived in, but may not have been recognized as a Sacrament. This is really not the place to discuss all the perticulars of your case. Divorce in itself would not prevent you from reception of communion, If you are not living with someone as if you were married, (shacking up) now, and your desire is to follow what Christ commanded, and the Church He founded teaches, you can go to confession and recieve the Eucharist.
I’m glad you came here to find out what the real story is, as it seems that some of the information you were given before asking here may not have been accurate.
So see a priest in a parish near you, and know that you will be added to the prayers of those who frequent this site.