What are these former things?

The redeemed will remember enough to remember the good and yet the bad memories will gradually atrophy and pass away in the mind.

Revelation 21:1 “And I saw a new heaven and a new earth: for the first heaven and the first earth were passed away; and there was no more sea.”

Revelation 21:5 “And he that sat upon the throne said, Behold, I make all things new. And he said unto me, Write: for these words are true and faithful.”

There is no disappointment, no sorrow, no sin, no one who shall say, I am sick; there are no burial trains, no mourning, no death, no partings, no broken hearts; but Jesus is there, peace is there. There “they shall not hunger nor thirst; neither shall the heat nor sun smite them: for He that hath mercy on them shall lead them, even by the springs of water shall He guide them.” Isaiah 49:10.

Pain cannot exist in the atmosphere of heaven. In the home of the redeemed there will be no tears, no funeral trains, no badges of mourning. “The inhabitant shall not say, I am sick: the people that dwell therein shall be forgiven their iniquity.” Isaiah 33:24. One rich tide of happiness will flow and deepen as eternity rolls on. { 9T 286.3}

Mark 12:27 
He is not the God of the dead, but the God of the living: ye therefore do greatly err.

“The graves opened, and the dead came up clothed with immortality. The 144,000 shouted, Hallelujah! as they recognized their friends who had been torn from them by death, and in the same moment we were changed and caught up together with them to meet the Lord in the air. [1 Thessalonians 4:17.]”

“In the future life we shall understand things that here greatly perplex us. We shall realize how strong a helper we had, and how angels of God were commissioned to guard us as we followed the counsel of the Word of God.”

Proverbs 4:23

Isaiah 66:22-23

"... from one sabbath to another, shall all flesh come to worship before me..."

“I saw that the Sabbath would never be done away; but the redeemed saints, and all the angelic host, will observe it in honor of the great Creator to all eternity.”
Spiritual Gifts; Volume 1; 113.1

Exodus 20:8 
Remember the sabbath day, to keep it holy. 

Leviticus 19:30 
Ye shall keep my sabbaths, and reverence my sanctuary: I am the LORD.

“And I saw a new heaven and a new earth; for the first heaven and the first earth were passed away.” [Revelation 21:1.] The fire that consumes the wicked purifies the earth. Every trace of the curse is swept away. No eternally burning hell will keep before the ransomed the fearful consequences of sin. One reminder alone remains: our Redeemer will ever bear the marks of his crucifixion. Upon his wounded head, his hands and feet, are the only traces of the cruel work that sin has wrought."

Isaiah 65:17

"... the former shall not be remembered, nor come into mind..."

Haggai 1:5

“We tried to call up our greatest trials, but they looked so small compared with the far more exceeding and eternal weight of glory that surrounded us, that we could not speak them out, and we all cried out, Alleluia! heaven is cheap enough, and we touched our golden harps and made heaven’s arches ring.

"the name of the wicked shall rot"