hello Panda13,
i myself was in your shoes few months back or at least in a similar situation. 9 months ago i have left w/ the kids due to my husband's cocaine use. it was difficult at first, as i doubted my decision, second guessed myself a lot, etc., but i stuck it out and waited it out to see if there will be any changes.
at first, i often wondered about him, his state of mind, whether he was ok, was he still using, etc. after some time (of no results) i have started shifting the focus from him to me and decided that i have to take care of me and the kids and that i cannot change what he is doing and constantly fretting about it is really pointless. now, after 9 months, i am feeling much better. now i find myself rationally thinking about him and evaluating his actions instead of just jumping and clinging to everything that was about him.
i guess in short, i wanted to answer your question, that yes it does get better. in time however. also it does require some work. i often go by that saying, "as long as we are doing the same thing, we can expect to get the same results". i have found great support here at SR and hope that you stick around.
as far as your question about staying in touch with him and checking on him, you can probably determine that by the way of how it affects you. for the majority, it is hard to detach, when we are still in the middle of it all. for me, it took me a long time of not returning his calls or texts (still don't really respond to him), but now, every once in while when i do talk to him, i find it easier to put the conversation behind me and not let it influence my actions for that day or however long. i can go on about my day and not worry about the things that he said or did not say, etc.
good luck to you and stay strong. time will help in answering your questions.
hugs and prayers to you. keep posting.