Oh, I thought you meant otherwise. Your following words suggested that you were referring to the type of engagement in which just willingness to marry someone is made public and no Nikah is solemnized.
dat u shod get engagd 2 da person u wana marry islamicly b4 da actual marraige...
Wanna marry Islamically? What do you mean? If you meant Nikah by engagement, then Nikah is to marry a lady islamically.
Nikah is marriage. After Nikah, there will obviously be a divorce if any of the parties want to untie the knot they strengthened.