how can i stop thinking about our memories together?

Just remind myself that some memories are even more valuable then the others that can be harmful or upsetting. There's new memories to be made, in a near or further future. Believe you're going to do much better and simply take care of yourself only, it's alright to be selfish for your own good once in a while. Be strong and know that there's many people out there that can help you and be with you for support in any way. You are loved by many. Memories can mean a lot, that is for sure, but there's those memories that are good and better that can be more memorable then those you built with someone who harmed you.