The first thing you should do is stop blaming yourself. You should ask for what you want. More importantly, you deserve to have your needs met. You don't miss your ex. You miss the idealized version of your ex. You miss the person you wanted him to be. Don't be fooled by your twisted emotions.

I understand though. I missed my ex for a few weeks until I realized what a broken, disgusting and spineless pussy of a person he is. He's an morbidly obese sex addict who will put his dick in any diseased hole, prostitute or otherwise, to get his fix, because no self respecting woman/halfway decent looking woman wants anything to do with him. The worst part? He's still married...lol. He lacks the balls to get a divorce, after FIVE(!) years. Instead of telling his hideously ugly and greedy wife to fuck off when she wants anything, he says, "Sure honey, how high can I jump for you?" He is the embodiment of a cowardly pussy. I laugh and shake my head at the old me - the old me who dated an unemployed loser who treated me deplorably. I recently began a new job at a place where a lot of people know him. It came out that I used to date him, and a man who knows him well looked me and said, "Who in the hell would fuck John Smith? What were you thinking?"

Make a list of all the bad things about your ex. It will be longer than you think and it will firmly plant your sometimes delusional mind in the center or reality.

Over time, I strongly suspect you will find that very good things will come over from this breakup. For me, that big thing was knowing my worth. My ex wasn't worthy of any woman even remotely like me. I'm worthy of someone amazing and lucky for me, I found him. My life is a million times better now that I'm in a relationship with a real man who is neither a cowardly pussy nor a dangerous sociopath.I wake up every single day with a sense of gratitude, happiness and hope now that I've found someone who cares about me, loves me, respects me and knows how to treat a woman.

You likely feel lonely right now, hence the reason you're having all these second thoughts. This too shall pass. The universe has something better in store for you. I can promise you that. I'm living proof.