what is the way to get remarried...?
will I have to kill my wife or is there a way I can get a divorce..

There isn't on consoles. The option should have been introduced with HF.

You cannot get remarried without mods.

Make a new character and marry the one you want to marry.

Can u tell me the mod please...
Also, what are the glitches that mod might cause

For PC only obviously, here are 2:

http://www.nexusmods.com/skyrim/mods/30339/?

http://www.nexusmods.com/skyrim/mods/9378/?

As it is a script function, once you have a save file with one of these mods active, disabling/uninstalling this mod can cause serious issues to your game. They also do not always work and might be incompatible with other mods (you can check the recent posts and the description)

you actually dont need any mod on PC just use console command to reset some relationship and restart the marriage quest by talking to maramal and buying amulet of mara again.

but that can cause even more trouble then mods can.

nope never has i always use console command to reset relationship rank and quest always worked for me i married 5 girls in single playthrough thanks to hearthfire's stupid home attacks

Yes, I agree that it hasn't caused any problems to any of my characters and I've done it quite often.

To the OP. Create a new text file and paste this into it...

player.removefac 51596player.removefac C6472resetquest 74793resetquest 21382setstage 74793 10

...then name (ex. divorce.txt) and save the file into your Skyrim\Data folder. Bring up your command console and type...

bat divorce

...twice. Wait a few days then go to Riften and speak to Maramal about getting married. You should be good to go at that point.