For me the key words to understand this Eucharistic passage is verse 13b, “having loved his own who were in the world, he loved them to the end.” He knows the betrayals that will take place, he knows the horror of suffering and the type of death , that awaits him, yet he loves his betrayers to the end… How? you may say, by laying down of himself in love and service of his betrayers. That is the significance of love, that comes out.
There is the significance of the Covenant also, which is sort of downplayed by John the Evangelist, by not consciously stressing on it. But yet he stresses on it. The Covenant is spousal, because this covenant will bind the Lamb of God with the Church, in and through marriage. And the self essence of marriage is self-emptying for the other, even if the other may-not respond in kind. This is how God loves man, in that he continued to love us and move us to being rescued, even though Adam/Humanity dumped him in Eden. The Old Testament bears witness to God’s Steadfast Love. Now Jesus is re-highlighting it. ‘love means self-outpouring for others,’ – this is the essence of God and within this essence, man discovers himself.
So don’t look at betrayals and highly charged statements of the disciples, in the Passion Narratives. Those actions are there to help us see God for who he is – Good and Steadfast.
So the practical exercise to go with this passage would be, to list everyone who you are uncomfortable, angry or have broken relationship with, and make a positive prayer of blessing and thanks in favour of each of them. Then ask Jesus to bless your sincerity and for Jesus to mend these relationships, so you may each day become like him in loving and being good.
To add, nothing that comes our way is bad, it is good and it is meant for us to grow in goodness. This we can understand by the fact that God is Good, and he watches over us, so he cannot let any non-good come our way. It is we who label things Good, Bad etc… Remove those labels, and appreciate God’s love for you, in and thorough everything you come in contact with or experience.