Has the Law Really Been Done Away With?

I recently took on the task of memorizing the Sermon on the Mount. Not long after that, I decided to preach it. What a response! That's not surprising: it IS the greatest sermon I ever preached. It may have been the greatest sermon anyone ever preached. I am sure I did not do it justice...however, God's Word will not return to Him empty. Since then, I have meditated on parts of it and have been immensely blessed as a result. I can trace almost everything I have learned and preached since then back to a principal found within the great Sermon.

Recently I have discussed the idea of tithing with some brothers and sisters in Christ. Forget what you know or have heard about tithing, that's not the point. My question to ponder today is whether or not the Law was really done away with. Yes, Jesus came to fulfill the Law. Does that mean it is done away with? Will we do away with Jesus?
Look at the Sermon, specifically Matthew 5:
"until heaven and earth disappear..." Has either of these things happened?
"You have heard it said..." In which of these segments did Jesus LOWER the standard of God's expectation?
In fact, in all Jesus taught - every parable, every word - when did He ever lower the standard?

Pause a moment.
I am not trying to bind anyone back to the Law.
We are saved by grace through faith...not by works. But...FOR works. (Eph 2:8-10).

Which of the 10 Commandments have we stricken from Christianity? Before you say the Sabbath, I would submit that we would all be better off with a day of rest each week. And the reason for instituting the Sabbath was that God worked (in Creation) 6 days and rested on the 7th.
Will we deny history?
Did not Jesus say (on multiple occasions) that keeping the two greatest commands (Love the Lord and Love your neighbor) takes care of all the Law and Prophets? If the Law was done away with, should we still keep these 2 commands?
Does the Sermon on the Mount apply to us today, or only to the audience of His time?
What do we do with Matthew 5:19-20?
May the Lord Bless you richly as you consider His Words.