I think you understood it already.
If God is love and love is not jealous, it is a perfect kind of love. There is no contradiction in it because God demontrates His righteous love for us. Another point: In other scripture says, you can be angry so long your anger won't lead you into sin. If you're angry with good reasons then clearly, there is righteous anger.
When God made this covenant with the Israelites He wanted to remind them that there should be no other gods before ME (Ex. 20: 5). Clearly God points this out that they should only serve Him.
2Cor. 11:2, speaks of betrothed kind of love, concerning their faith of the ungodly. This jealousy pertains to the love of the world more than the love of God. Often times, we fall into worldy posessions, relationship, marriage, lifestyle, covet other greeds and what have you, God will be a consuming fire (Deut. 4: 24), when we betray our love for Him. He has the right to be jealous.
Point to ponder: God also a jealous God when He created us He made each one of us His children. When His children grew up and disowned Him, how would He feels?