Hi Laura, this is a difficult question because I completely understand you I have in someway done kind of the same thing as you… But it is a viscous cycle as you will already know and if you don’t get over it now then this problem will always arise in any relationship your in. I understand how hard it is but what I think is its nothing to really do with your boyfriend it’s to do with you, i feel you need to work on your self love and realise everything you’ve been through and how strong you were to leave your awful ex boyfriend. I have the same issues with me and my boyfriend but what we really need to do is work on ourselves. Don’t worry about him leaving/cheating because you don’t know if that will ever happen and if it does then you will move on and it will make you stronger but don’t worry about something that hasn’t happened yet. Also if he is moving to be with you in 3 months he must care about you a lot. Don’t loose him over little things you can work on, if you think he is worth it and is offering you everything you need to believe he’s a good boyfriend then trust him. Hope this helps
Lots of love