The question you should ask yourself is, what are you trying to gain from contacting him? Sometimes closure is an excuse that people subconsciously use to get in contact with their ex. True closure comes from within. Its been 3 years. You're only going to end up opening a can of worms. All the closure you need is knowing that it didnt work out.

How would you feel if he declined your invitation? And you should tell your mutual friends that they should stop talking to you about him. Because it sets you back. Dont do this.