I hate being self-aware and promising myself I won't do certain things again, but they still happen, although I have definitely gotten better with some things and not repeated them. For example, I was very manipulative and threatened to kill myself if my first ex-GF left me. I realised straight after saying it that I shouldn't have and I've never said it again to anybody. It's just that I'm still quite controlling in relationships and am quite manipulative still. I don't want my next relationship to fall apart mainly because of me again. I just never know if what I get upset over is valid or I'm just being too sensitive and naggy. My previous ex-GF was on Discord with her two friends 85% of the time while with me when we met. She was also on her phone the whole time we were in the restaurant on our last meeting while I tried to converse with her. She even brought two portable phone chargers with her so her phone wouldn't run out of power while we were out. This made me feel very upset and insecure and the whole situation blew up when I brought up what was upsetting me. I just don't know if it's normal for couples to be on their phones most of the time while with you? What's normal and what isn't? What can I be upset over and what can I not be upset over?  How do I communicate effectively what I need in a relationship and communicate when a partner has upset me without making the situation escalate? How do I stop making partners my everything and my moods being dependent on them when I know how unhealthy both are? I'd just really like a healthy relationship that lasts and not an intense one that falls apart in a month. 

I'd greatly appreciate any advice on this.