How many Gods is there in the Catholic belief?

I was brought up in a Lutheran home. My wife 2b comes from a catholic country.
She is studying at THS, Stockholm school of Theology, that means she has left the catholic church and now studies Christian religious history.
That is a very interesting subject, so I read just for fun too some of her literature. When we spoke about Luther and the ten Commandments we came in a dispute.
She did not understand what I was saying about the first! (Free translation, NOT from goggle translate:"You shall have no ther Gods than Me!")

Thats not right she said, it is "You shall put no other Gods in front of Me!".

After a small discussion we entered Wikipedia, and to her native language about the ten Commandments, spanish: "Amarás a Dios sobre todos las cosas"
That means "God above everything" nothing that there is only one!
Strange, I thought, and looked in english.
According to this catholic link it is:
"I am the Lord your God, you shall not have strange gods before me!"
Before me...Doesn't that mean in front of me? I translated into Swedish with google translate. It translated like I wrote before, but when I changed "gods" to "cars" it translated "in front of me"...
Even this link, commenting on how the catholic church tries to change the gospel (by changing the day of the sabbath which was foreseen in the Bible in Daniel 7:25), writes the same. (this is who that link belongs to: a remnant church. I do not say anything if they are good or bad, I do not know, but they wrote interesting there)

I know we have the same Bible, and if you read there you surely can see all Christians only have one God, but Luther had a good point in really writing that.
He saw how the catholics were praying to saints and reliques, just like they had devine powers. He saw people drinking "holy water". In his eyes it looked like those things where like sub-Gods, minor gods. You still may see that for example in South America were the drivers are saluting to all the crosses over people killed in accidents to make the spirit help them to a safe journey.

What is right and what is wrong? If you wonder, no matter what religion you are (or atheist and agnotic), look in the Bible yourself. The truth, what the Christians (and Jews) shall belive in, is written there (but if they are right about only one god, that is another question)