Spirit Of Jealousy

In Numbers 5, jealousy is dealt with in the law:

12 Speak unto the children of Israel, and say unto them, If any man's wife go aside, and commit a trespass against him, 13 And a man lie with her carnally, and it be hid from the eyes of her husband, and be kept close, and she be defiled, and there be no witness against her, neither she be taken with the manner;

This law involves adultery on the part of the wife when there are no witnesses or that she hasn't been caught in the deed.

14 And the spirit of jealousy come upon him, and he be jealous of his wife, and she be defiled: or if the spirit of jealousy come upon him, and he be jealous of his wife, and she be not defiled:

When there is no proof, there is the possibility that she is innocent. The problem is that jealousy can enter the relationship and by it's nature it can be violent involving rage and out of control emotions.

Proverbs 27:4 4 Wrath is cruel, and anger is outrageous; but who is able to stand before envy?

Envies and jealousies are cruel because they go after another person in a bad way. Gossip, lying and extreme emotion may be its vehicles, in one person trying to destroy another. It can lead to even more damaging consequences. Throw in some control and indignation and it can be quite a recipe for evil. Adultery is wrong, but so can the reaction to it be wrong.

15 Then shall the man bring his wife unto the priest, and he shall bring her offering for her, the tenth part of an ephah of barley meal; he shall pour no oil upon it, nor put frankincense thereon; for it is an offering of jealousy, an offering of memorial, bringing iniquity to remembrance.
29 This is the law of jealousies, when a wife goeth aside to another instead of her husband, and is defiled; 30 Or when the spirit of jealousy cometh upon him, and he be jealous over his wife, and shall set the woman before the Lord, and the priest shall execute upon her all this law. 31 Then shall the man be guiltless from iniquity, and this woman shall bear her iniquity.

In the Old Testament this is the way things were dealt with. In the New Testament, with the presence of the spirit of God in the believer, Paul records the ultimate reaction to evil:

3 For though we walk in the flesh, we do not war after the flesh: 4 (For the weapons of our warfare are not carnal, but mighty through God to the pulling down of strong holds;)5 Casting down imaginations, and every high thing that exalteth itself against the knowledge of God, and bringing into captivity every thought to the obedience of Christ; II Corinthians 10:3-5

Galatians 6:1Brethren, if a man be overtaken in a fault, ye which are spiritual, restore such an one in the spirit of meekness; considering thyself, lest thou also be tempted. 

Check out Ephesians 6:11-17. The world is full of jealousy, envy and strife.  God is the answer to it all. It is in his hands how forgiveness plays out. It may involve restoration, but it could involve putting distance in the relationship when things are not restored.  Our attitude of meekness toward God is the primary determiner.