it's difficult when you're emotionally involved with someone but hindsight is a wonderful thing.
in my mid 20's i allowed my then bf to move in with me temporarily when he got thrown out by his parents (that alone should have set the alarm bells ringing). He knew from day one that i expected him to get down to the council and start sorting his own accommodation out - but i ended up sorting out the paperwork for him because he wouldn't/couldn't/felt embarrassed 
i was unemployed at the time - I used to get roughly £40 a week JSA. After paying my water rates, topping up the meter for gas n electric and buying the groceries and essential toiletries etc for that fortnight i had literally £1 left over per week - which i used to treat myself to a McDonald's value double cheeseburger 
He complained that i was 'tight/stingy' for refusing to put heating on and expecting him to wear extra clothes - didn't seem to understand that the gas & electric had to last a fortnight for cooking, washing/drying clothes and hot showers. He also didn't seem to realise that switching on lights, charging phones (and his laptop) used electric - or even that the meter continued to charge me even if it no credit on it so i still had to pay that debt the next time i topped up. He complained about having to eat Smart Price food, it was 'shit' quality apparently - not like the brand stuff his parents bought! Apparently living like a 'pauper' was ok for me but not for him!
I told him beggars couldn't be choosers and if he dared to talk to me like that again - the ONLY person who was willing to provide a roof above his head and food in his belly- then he could go sleep on a park bench and eat at the homeless shelters like others who's circumstances left them with no other choice.
like you, i too have a big heart and due to my own shitty childhood grew up feeling like it was my responsibility to help/sort out the problems of those i was involved with/close to me. I used to feel i was being mean, petty and selfish if i didn't. It was me who had to force him to sign on so he had some income. I was being 'unreasonable' apparently when i expected him to pay half his jsa towards the living costs 
we were both smokers, but whereas i could go without if i couldn't afford it he resorted to stealing to satisfy his craving. he would tell me his 'mates' bought it for him - until i found out he was stealing the packs left around by the builders working on my block.
A couple of months after he moved in i got a job - but i still expected him to live by my rules in my flat and i refused to buy him cigarettes or beer. He had this idea that me working meant he was entitled to have better food,heating on all day, nights out and cigarettes and beer paid for by me! Lmao! I couldn't even afford that for myself so soon after starting work and paying full rent and council tax so i don't know why he thought HE was entitled to it out of my earnings.
I don't like living with people, i'm one of those that needs a lot of time to themselves and i HATED coming home to find him sprawled on my sofa, playing on his laptop not having done any housework and breathing in my space. Some might that peculiar but that's how i am and feel and i make no apologies for it.
I was accused of 'nagging' him....because i had to tell him to clear the plug hole of his hair - EVERYTIME he used the shower, clean the toilet instead of leaving the skid marks and piss on the seat and floor, because used tea bags go in the bin - not left on the side of the counter to grow mould (it takes the same amount of effort for gods sake!), because his dirty football gear needed to go in the washing machine and HE had to press the buttons to wash it and then hang them out to dry. I felt like his MOTHER, i even had to tell him to shave and brush his teeth! I never had the privilege of being 'mollycoddled' or 'mothered' in that sense and i resented having to do it for him.
he'd never lived on his own or had to fend for himself, his mum and dad used to do everything for him and provided everything for him. The highlight of his 6 month stay in my home was when he complained to his parents that i was charging him HALF his income to live at mine - and they pointed out to him that they, and I, had been providing for him out of our own pockets, and now that he had some money coming in it was only fair that he contribute towards his upkeep! He had convinced himself that because his parents and i would be paying household costs even if he wasn't living there that meant that a) him being there didn't really cost us much in extras and b) he should only have to pay for his food and personal stuff because asking him to contribute towards rent etc was just cheeky!
i threw him out on windy, rain drenched november evening when i came home to find that he'd been rifling through my suitcases and had stolen the bag of pennies (amounting to £17 that i had forgotten i had) so he could buy cigarettes. If he hadn't been so stupid as to leave the carrier bag behind with the strip of paper stating the amount i never would have realised. Idiot! Funnily, up til that point i had been feeling 'responsible' for him, but when i found out he'd stolen from me something snapped inside. i confronted him, he gave me the same sob story about being 'sorry', how he felt like killing himself cos his life was shit and unfair -this time i just heard myself saying "ah boo hoo! aren't you a very special snowflake?! it's called 'real life' and taking responsibility for yourself. I too feel like life is too much for me to handle right now, i don't even want to be alive most days but i don't have the luxury of wallowing in my self pity and neither can i afford to - so why the fuck are you expecting me to make it possible for you? Get out - right now - i don't care if you have nowhere to go but the park bench. you've had 6 months to get that sorted and i'm not letting you stay here for one more minute so you can steal and take the piss even more"
i didn't feel guilty or bad once i'd said that. he was old enough and intelligent enough to have self awareness but chose to play the 'i'm helpless, mentally fragile' card to manipulate me into 'keeping' him. Last i heard he was sofa surfing at his friends house - until they made the mistake of giving him the rent money to pay in and he stole it. They couldn't afford to get another £350 together and ended up being thrown out of the house they'd been living in for a year.