I'm late to this, but here's my few pennies -
I was in law enforcement for a tad over twenty years and ironically enough, I'm now in school full time studying psychology - so I'm sort of going backwards from you I suppose. You said this was your first "professional" job implying that you've had others (jobs) before that. I've worked at a ton of different places in my life (42 years old) and heck, just in the last few years I've gone through six jobs while I've been trying to figure out what I want to do when I grow up (mainly because we relocated to Texas to try and start over financially, so we've been spinning our wheels trying to find decent employment while my wife and I both try and get through school).
Assuming you have other things to put on your resume, I would either leave your most recent place off of your resume or simply tell prospective employers you do not want them contacting the previous employer due to "unresolved issues/management conflicts". You've got your education to fall back on and that should enable you to find something. As for whether or not you really want to get into law enforcement or not, I'm not so sure. I got out of it after 20 years because of various issues and much of the nonsense I'm sure you've all seen in the media lately are some of those. I saw the writing on the wall so to speak and I really think law enforcement is going to be facing some serious challenges in the years to come - it's not what it is cracked up to be and it's going to get worse. With your background, I would look more towards getting a civilian psych job with a department (what I want to look into doing) rather than a sworn position, but that's obviously up to you. Depending on your age, be aware that some departments do have age restrictions for getting in (since you said you are in your 30's). The police stuff I can help you with if you want to ask questions