I think that being raised in a household with a parent who had an addiction is crucial, here. It's not unusual to follow that with adult relationships with addicts: we're used to it, it's familiar, the substance is always the priority, and we understand that pattern of our feelings not being a priority.
Your feelings are a priority. This is the switch you need to make. If you can do that, and recognise that you need to put your own feelings first, you'll transfer from 'He's happy/sad/on the moon/whatever, and it makes me feel really shitty, why does he get to be happy and not me, why does he get to have a good relationship and I don't, etc' (which is his life dictating your emotional state) to 'I don't feel good at all. What can I do to make myself feel better? What things make me feel good/better? How can I plan them into my days/weeks ahead, so that I feel better more of the time? What do I need in my life that I don't have now, and what steps can I take to resolve that?'
Do you see the difference? The first is about him, the second is about you. Your childhood taught you the pattern that it isn't about you, but it is. You have to look after yourself like you'd look after a child. What do your emotions tell you? 'I'm miserable, sitting here in this chair, crying about my ex', so, what would you do with a child who said similar? (crying about their lost teddy, for example) You'd encourage them to come out to the park with you, right? Or give them a hot chocolate? Or get out their colouring books? You'd distract them from the shittiness by offering something nice for them instead.
The child inside you didn't get heard, and she's the one who's crying. She's crying because your parent drank, and she's still not being heard, for the same reasons. When you start to respond to her, by putting her first, she will mature. She's the one who's referred to as your 'gut instinct'. She's very very wise, but like everyone who isn't listened to, she's very very upset.
What does she want? What would make her feel better? Is she just upset or is she angry too? Or tired? Or all of those things?
Once you hear her and respond to her, she will be your self respect.