The hadith: “Conceal the engagement and proclaim the marriage”
Question

Is it forbidden for muslims to declare the engagement (alkhotoba)? If yes, who are the people supposed to know about the engagement?
Are Close friends allowed to know about it??.
Praise be to Allah.This hadith was narrated by al-Daylami in Musnad al-Firdaws, where it says: “Announce the marriage and conceal the engagement.” This is a da’eef (weak) hadith which was classed as such by al-Albaani (may Allah have mercy on him) in al-Silsilah al-Da’eefah (2494), and in Da’eef al-Jaami’ al-Sagheer, 922. 
But the first part of it is saheeh with the word “proclaim.”  
Ahmad narrated from ‘Abd-Allah ibn al-Zubayr (may Allah be pleased with him) that the Prophet (peace and blessings of Allah be upon him) said: “Proclaim marriages.” This hadith was classed as hasan by al-Albaani in Irwa’ al-Ghaleel, 1993. 
Proclaiming marriages, in the sense of announcing them and publicizing them, is obligatory according to the majority of scholars, indeed it is one of the conditions of a marriage being valid, because the Prophet (peace and blessings of Allah be upon him) said: “There is no marriage except with a wali (guardian) and two witnesses of good character.” Narrated by al-Bayhaqi from ‘Imraan and ‘Aa’ishah; classed as saheeh by al-Albaani in Saheeh al-Jaami’, 7557. 
Some scholars regarded it as mustahabb to conceal the engagement for fear of hasad (destructive envy) which could lead to trouble between the man and the family of his fiancée, as stated in Haashiyat al-‘Adawi ‘ala Sharh Mukhtasar Khaleel, 3/167. 
This is supported by the words of the Prophet (peace and blessings of Allah be upon him): “Seek help in meeting your needs by keeping quiet, for everyone who is blessed is envied.” Narrated by al-Tabaraani; classed as saheeh by al-Albaani in Saheeh al-Jaami’, 943. 
This does not apply only to engagement, rather a person should not show openly the blessings that Allah has bestowed upon him to one who will envy him for that. 
With regard to holding engagement parties, this is something that many people do, and there is nothing wrong with that in sha Allah. But it should be noted that we must adhere to the limits set by sharee’ah in these parties, so there should be no free mixing of men and women, or use of musical instruments apart from the daff, because the Prophet (peace and blessings of Allah be upon him) allowed use of the daff in wedding parties. 
And Allah knows best.