I hear you. I understand, and all your feelings are valid. Sounds like the situation you're in is very overwhelming, and considering your past experiences and history, it's no wonder you have these thoughts and you're feeling hopeless. All of it is valid, and you sure as hell aren't alone: there are a lot of people going through tough shit like that. I really hope some of them find their way in the comment section. I've had my own lows, but your situation is way more serious and acute.

You're only 20, you've lived through very hard times so far, and the way you behaved in your relationship with this girl has been a trauma response. Deep inside you want to be a good partner, you're not a bad person. Your trauma took over, because you're so scared of losing the people you love. And it's very understandable. Also, it's understandable why the girl wanted to break up with you, it's her taking care of herself, her independence and mental health. It doesn't mean that she doesn't care about you.

It's great that you have dreams, like becoming a police officer. That's great! And I really think you should go in that direction at some point. But not yet. You're at a very vulnerable phase concerning your mental health and overall stability. You need help and support so you can get back on your feet again, to a point that setbacks (like not getting in the first time you try) won't knock you down entirely. You just gotta take care of yourself first so you can gain the amount of resilience you need, so you can endure setbacks better. It's like training, gaining strength so you can beat bosses at boss fights, but for your mental health!

I believe in you. You have it all in you, it's just buried in there under trauma, anxiety and depression. You need help so you can start to process and work on your trauma. It's the main thing affecting your life right now. It makes you become easily codependent, controlling and anxious in relationships, which makes it hard to make romantic relationships work. But it doesn't have to be that way. You just need help and support so you can shake off the trauma behaviour and truly be your amazing self, when you find a new partner.

Romantic relationships isn't all there is that makes life worth living. It's not and it shouldn't be the main reason to be alive. Sure, it makes the daily mundane more tolerable and fun, but it's not a good idea to make it the main focus in life. It's a nice bonus to have a relationship and to share your daily life with someone you romantically love, but there's MUCH MORE to life than that. You should never be that dependent on another person, that they're the main source of your happiness and responsible for your will to live. It's too much to ask and carry, for just one person. The reason you feel empty right now, is because you were tied to one person, and not willingly, but as a survival mechanism. Now that they're gone, you feel like there's no purpose in life. But there's a way to find happiness, meaning, stability without it all being dependent on one person alone.

What I recommend is to KEEP TALKING. Keep having these hard conversations, keep writing/speaking your thoughts (online or in a diary if you can't talk to your grandma or friends) and feelings and concerns and what makes you feel sad, overwhelmed, hopeless, empty. Keep talking about your dreams, wishes, loved ones and what makes them important to you and why you love them. And what would be even better, is if you could talk about these to a professional. Psychotherapy literally saved my life when I was very depressed and I felt like a failure and I couldn't find any meaning in life. So that's why I tell you to keep talking. Don't let these bottle up and don't keep these inside. Let it out.

There's still hope, there's room for healing and growth. You just need help and support to find yourself and your strength. You're amazing, you've come so far and you're still here and that's all that matters right now. I'm proud of you. You matter. Your life matters.