It’s the most important question, isn’t it?: Who goes to hell? – Only God knows!
… HOWEVER, God in His goodness has given us a few points of reference for avoiding hell and getting to heaven. We need to be humble enough to follow His “advice” - aka “the Catholic Church” ( Go to Mass for goodness sake! )
I had dinner with a friend Sunday evening. He told a friend of his (a lapsed Catholic) that he went to confession, and the other guy said “why? can’t you just ask God for forgiveness?”
My friend’s response was - “well, i can’t forgive myself - God is the One Who forgives me.”
Good answer I think. While it is true that we can go directly to God with an act of contrition and be confident of forgiveness for venial sins, serious sins are a different matter.
I heard once from a priest what i think is excellent advice: whenever you have committed an offense against God that is “grave matter” or you think might be a mortal sin,
pray at once for forgiveness, make a firm resolution and plan to
break with that behavior, resolve to
go to confession at your earliest opportunity, and then
go to confession!
This way we can
live at all times with sanctifying grace - a firm hope that we will be saved!
We simply have to live in the reality that sin is the only thing that can separate us from God. The best way to do that? I like the suggestion I heard from Karl Keating once when he was making arguments against “faith alone” for good works: If we fill our life with doing good works - prayer, works of service, anything that pleases God - we won’t have time to sin!
It is entirely possible that getting into heaven is a lot harder than is generally believed in polite society. However, God says it is overwhelmingly worth it! “Eye has not seen, nor ear heard, nor has it entered into the hearts of men what God has prepared for those who love Him.” (1Cor2:9)
I have also heard it said that God does not send us to hell as much as we choose hell when we don’t follow in our lives what God has revealed is necessary to live with Him. Luckily, if we stay close to the Church and follow her teachings, mortal sin is improbable - at least that is what i have heard from Fr Groeschel and others on EWTN. At the very least, your conscience will sound out loud and clear if ever you should fall into mortal sin, in which case you can follow the emergency plan above and
go to confession. (am i saying that too much?

) God’s laws are spiritual, but they are like the law of gravity or any physical laws which the physical world conforms to. We can’t escape them. God is good - infinitely so - and if we are not also good we are implicitly using the free will He has given us to choose other than Him. Basically we are rejecting Him.
The good news is that God is also infinitely merciful. He gives us every chance He can. But in the end it is our choice. Will we develop the humility to say “whatever you tell me to reject as bad, i will reject as bad, and whatever you tell me to embrace as Your will, I will embrace.” Will we have the humility to say this and mean it at the time of our death?
Basically, I don’t think salvation “just happens”. That’s not to say we earn our salvation - it is a gift of grace, and we could never possibly deserve the wonderful things God promises those who love Him. But even to accept the gift honestly takes some work on our part. Because God basically gives us what we want at the time of our death, we must be careful not to form strong attachments to things which are sinful. We “choose” implicitly by what we love. Do we love God’s ways? Do we feel blessed to even know what they are? Shouldn’t we share this incredibly advantageous knowledge with others who are not Catholic?
Anyway, as the OP has said, our great consolation is that God is infinitely merciful - however generous we are in obeying His commands, He will out-do us with His generosity towards us. That should be a great comfort to us. But we have to be honest with ourselves, because He will not bring us to heaven against our will, if what we truly want is our sin. And so the closer we stay to Him every day the safer we are. Don’t wait years before
going to confession!
hti.umich.edu/cgi/r/rsv/rsv-idx?type=DIV2&byte=5593993