Maybe I am a bad player

Played with $18,000 over the last few days, withdrew $1600 to pay for musical equipment and rent. I've been losing a bit every few days, not playing much because of my incredibly low confidence.

Tonight i lost $4500. $1000 i lost my own fault, then i made $100 and cashed out (so about $475 down), that was on $25/$50. on $25/$50 i put in $1000, playing from 4 to 7 handed, there were a couple of loose players, one in particular. i managed to near double up off him a couple of times, to build to $3500, lost a bit then back down to around $2k, before getting up to $4k, then this happens. playing a $3761 stack, i have K9 suited. and raise on the cutoff, playing 5 handed. called on the button by a fairly loose player (guy who won $15.6k pot against me some months ago). flop comes 5710 rainbow. i bet $250 into $370 pot. called. turn a 9 of diamonds, making a possible flush draw. i check, and fires £800 into $870. looks like hes drawing to me so i make it $2200. he pushes, which leaves me $1161, perhaps i should lay down here as i think im some way behind now, but its only $1161 into a $7595 pot, he shows 1010 for a flopped set and i'm drawing dead. i guess it looks like a stupid play by me (the raise on turn), infact i won't defend it, i made a bad decision and paid the price. i think i may have understimated him as a player (or rather thought he was a looser player than he actually is), especially him calling with 1010, i thought he would have raised something like that, maybe he is trapping or maybe it was because i was playing fairly tight.

i had $3k left in my account, which i put straight in. early on i get up to £3525.70 when i was dealt KK on the button, folded to me and i raised to $250, called quickly on the sb and the bb folded. flop comes 689 with 2 diamonds. check by him, i bet $550 into $545 (i think), and he calls. turn is a J, not a diamond. the pot is $1645. if he is flushing or has one pair, which is what i'm thinking i desperately don't want to give him a free card. i reckon i would probably check here alot to stop the pot building up too much. anyway i did bet $1300, enough not to give him odds, he moved over the top all in though, leaving me with $1425.70 for a potential pot of $7096.40. i figure i'm probably losing right here but it's really difficult for me to fold and there's always a chance i'm winning against this player (he's not a bad player just someone who plays alot of stts so someone who is more likely to make a play or even move in with a big draw), i'm beating j10 here (probably raise pre-flop) or very unlikely 2 diamonds (with a pair or gutshot too perhaps?). possible he has a set or two pair but he would prob raise on that kind of flop. the most likely hand i have is probably 2 medium cards, 78s or something like that with a pre-flop raise of $250 on the button but very difficult to pin it on just medium cards. 75s also a possibility. anyway, i do call and he turns over 99 leaving me 2 outs which i don't hit. 2 situations there against sets i managed to lose all my money with just a pair, i'm not 100% if i should be folding the KK though because i have committed a fair proportion of my stack.

not sure how many readers i get on this blog, have tried to get it more broadcast but maybe my writing is as bad as my playing :( i really need to stop losing otherwise i will be broke within the next 1-2 months. for both of these $7k pots should i fold on the river or am i pot committed? (anyone who reads the blog can answer that) because i've thrown away over $2500 calling on the river for these 2 pots (accumulated). On the other hand maybe the risk is worth the reward.