Simone - you need to get a restraining order or aprehended violence order or whatever it is called against the XH. If you have one and he breeches it then you do not need his permission to leave the state with Declan. Also (have read your punhing bag post) I would be heading back to the poilce, and demanding to speak to someone else. I would be seeing my doctor for a report to.
Scratches show instently (and bravo there babe) but bruising takes a while. Get photos, get medial reports, note swelling (ie your knee).

Have Xanders tantrums improved?... do you think the home situation has made them worse?