Addiction isn't a friend to anyone, not the addict or the addict's partner or family. This ex was just wanting you to be his enabler and fit into HIS lifestyle pattern. You ended up breaking down and finally realized you could no longer psychologically deal with living your life according to HIS wants and needs. It sounds like you tend to end up in relationships where you fall into living your life according to your partner's needs and that is what you are used to what you know HOW to do. This is probably due to the environment you grew up in where you had to learn to live around the needs of others so when you end up with a partner you unknowingly pick a partner that puts you into that very same role you played that was familiar to you on a subconscious level. Alas, we are creatures of "habit" so that can mean we unknowingly choose unhealthy patterns simply because it's so ingrained in us. When you "miss" a partner even though that partner was unhealthy to live with, you are missing the pattern the most, NOT the person. A lot of people make that mistake, myself included, so don't beat yourself up for it and give yourself a chance to get used to no longer following the pattern you got used to living with. The human brain is set up to "learn" by doing and that's what you unknowingly did. Old habits die hard, well, that saying is true and the older someone gets the more ingrained these habits get and it's hard to let go of them, it's that way for everyone.