My husband and i decided give anal sex a try and now a week later and it still hurts and there is like a constant pressure in there. will this go away?

YES: When tissue(s) not used to trauma even if mild still REPETITIVE they SWELL and this is a reaction to the trauma (much like a bruise or muscle aches after extreme exercise) swell and HURT. A week is not an unusual amount of time for RECOVERY! If you are still uncomfortable in another week see your Gynecologist for a check-up!~ Hope this helps! Dr Z