First of all, I'm a newbie at posting hands so please forgive me if I've make any mistakes anywhere in explaining this hand.

My image is super tight. I am known as the tight player on the table, and everyone is always wary when I play a hand.

UTG+1 is a loose player, calling with many holdings preflop. He limps AQ AJ and even AK. But tonight he was raising preflop more, so I suspect he was raising AK instead of limping it. Postflop he tends to cbet when everyone has shown weakness. Known to bet pure air or gutshot into 2 people when weakness shown.

I had about $120 (60bb) and UTG+1 covers with ~$400 or so (200bb)

1/2 NL 7-handed. Straddled to 4, calls around. I call with A 9from SB. BB completes. Straddler checks.

Pot 28.
Flop comes A K 2

I wasn't paying attention and dealer missed my turn, BB checks, UTG checks, UTG+1 bets 12. fold fold.
Now I realized I missed my turn and told everybody about it. But in the end I opted to just skip my turn and call his bet of 12.
BB (standard player, no special reads) calls 12.

Pot 64.
Turn comes T
I check. BB checks. UTG+1 bets 22. I call. BB folds.

Pot is now 108.
River comes 5
I check. UTG+1 immediately and calmly bets 65. What would you do here? and what do you think of how I played the hand

Personally, I would fold to the straddle Preflop. A9 off out of position is asking for trouble. It very often leaves you calling off flops like this all the way down, and almost always you are beat here.

I really don't think the 3rd diamond changes much. I feel we were behind the whole way, and the villain is milking us like a cow.

^^^ This.

SPR is actually only 4.3 on the flop. It's a huge pot going to the flop and you only have $120, I'm raising the flop and committing my stack. Hearts can call us, KX can call us. There's not a whole lot that beats us on that flop. A2, 22, AJ, A10, that's about it. I'm raising to $40 on the flop.