Struggling with the Catholic Faith

I want to try and make this as quick and straight forward as I can. I grew up in the catholic faith and I believe in God and Jesus Christ as my Savior. I have 2 young kids ages 5&3 both baptized and going to a local Catholic School. I recently started wearing a miraculous medal because I feel like lately I am being spiritually attacked. At the same time, I struggle with sins in my life. I find myself occasionally getting angry at my wife or the kids, I struggle with swearing all the time, and I struggle with lust. Lust is a tough one because it can be committed through simply human desires from our thoughts and the current state of the world offers no help to anyone struggling with it.

When it comes to the catholic faith, I struggle to understand some of the specifics to Catholics, I am realizing that some of my understanding of the faith might be mixed with Protestant or Christianity and this is where I start to struggle with it. I believe in God, and Jesus who died on the cross for all of our sins; past present and future but is this true? This isn’t the catholic belief? It suggests we are all saved through Jesus regardless of sin and we all go to heaven. But what about the thief on the cross beside Jesus who was spared a place in heaven. And even though he never repented he was offered salvation through his faith in Jesus. But that’s not necessarily what I believe the catholic faith teaches, and please correct me. Catholics believe the blood of Jesus opens the door for our salvation but we are still required to do the work of God and repent all of our sins before our final hour that we have no understanding of when our time will come or else risk an eternity in hell separated from God, and if we fail to repent before our times up we’re destined for an enter it’s in hell. This seems like an impossible task. Even if you followed God your whole life but you made a mistake before you died, whoops.. sorry. To Hell for you! What is the truth? Are we saved through Jesus Christ as I have believed my whole life or are we not? By the catholic faith it would seem nobody is going to heaven as we are all mortal sinners but are we not already saved and offered the gift of salvation through Jesus Christ?