I'm currently playing a paladin, 3 levels, and 1 level warlock. The character is one that was in a terrible war and now hates fighting or hurting others and they also have PTSD. They can and will fight if it's in the defense of others otherwise they don't really want to and will take damage until life threatening. They have fears of having an episode of PTSD and hurting others with their skill set because they don't hold back during these episodes.

I understand that I chose to play a very counterproductive character but I didn't want a cut and dry paladin. I wanted a character with a lot of flaws and one that had room to grow.

Any ideas on how to utilize the defense aspect of the paladin? I know there isn't much defensive spells until much higher levels but warlock doesn't have much in way of defense. I chose warlock for ranged attacks, whether to protect or during an episode of no control. 

Thank you

I think your best defense against your flaw is going to be an RP one, rather than a tactics one.  I think you're character is going to have to do a LOT of very creative problem solving and a LOT of staying on top of problems early to embrace a policy of non-violence and also fulfill the tenets of their Oath and ALSO fulfill the demands of their patron.

Assuming you're still in the process of tweaking the character, the Oath of Redemption gives a lot of nice choices for someone like your describe.  Their oath spells include Sleep and Calm Emotions, which are dynamite for non-violent problem solving.  Its Channel Divinity opinions are a +5 to Persuasion or a damage reflect.  I don't think that helps you're guy though, since he wants to prevent any damage.  Oath of the Ancients includes a restraining Channel Divinity option.  I'd also probably pick Defense as my fighting style instead of Protection.

On the Warlock side, Archfey has a mass charm effect at level ONE.  AND they already have Sleep and Calm Emotions on their spell list!  Celestial has a heal, but again, that's not as good as a prevention.  No one else seems like a plausible patron for you to pull this off with, honestly.

So, if I were starting this person from scratch, I'd for sure go with Oath of Ancients/Archfey Patron OR Oath of Redemption and either Celestial or Archfey if you can talk your DM into it.  If I had a feat to work with, I'd take either Sentinel or Lucky.  There are a dozen races that contribute SOMETHING or other to the project.

The non-violent Paladin's best defense aspect is his high CHA.  The first rung on the Ladder of Escalation is to co-opt and persuade or at least dissuade.  In addition to the social skills, you need Perception and Insight to figure out how big a threat you're facing and how to negotiate out of it.  Cantrips like Prestidigitation and Minor Illusion can be great for defusing social situations before they turn into barroom brawls where your character is going to have to hurt someone.  Cast Charm Person on the Warlock side and turn an enemy into a friend.  If I had Calm Emotions, this is when to use it.

Next on the ladder of escalation comes Deterrence - whether by threat or by increasing risk or distractions.  Insight helps here too because you know what your counterparty holds dear. Use Intimidation and Cause Fear, maybe an appropriate Pact power or Channel Divinity.   You give yourself a lot more options in this area by confronting situations quickly and thinking outside the box.  This could mean hiring a few thugs to look like you have more backup than you do, or pulling the fire alarm, or Prestidigitation-based ventriloquism.

Now your next option is Defeating an Attack.  Heavy armor and Shield of Faith will keep you safe or else Command Duel or Sentinel feat will keep things focused on you.  This is where I'd cast a spell like Sleep.  Ensnaring Strike, Command to "flee" or something.  This is where it goes. 

Okay, the attack was neither avoided nor defeated.  Now you can only deter it from happening again.  I can't, in good conscience, not mention that if you wait until you've got life-threatening injuries before you fight back, you're going to die and not be that helpful.  But you sort that out yourself.  Now, the line has been crossed and you're lashing out with everything you've got.  This is where you use whatever spell slots you've got on divine smites.  This is where you take advantage of the battlefield and shove a guy off a roof or into a gelatinous cube.  You've bet everything on winning a fight with a last second blow, so find the thing that will do the most damage and use it.

I assume you went with the Redemption Oath for the Paladin Oath? Finding peaceful solutions to conflicts is pretty much their whole deal. Their expanded spell list comes with a few really nice ways of either stopping a fight or stopping individuals from fighting and if a fight can't be stopped it comes with some nice ways of protecting your friends.