My parents would say the exact same thing, us favouring in-laws led to our estrangement. In reality my parents being nasty and toxic caused us to favour the in-laws. They constantly gave us the silent treatment when we didn't do what they wanted or called us stupid for not following their advice. Generally if you were complaining or turning everything into a competition then they would've wanted to spend less time with you.
Jealousy is only human and we all get it. Doesn't make us a bad person at all. However you have to realise that couples can't spend their time making sure that both parents get exactly the same treatment (like two kids carefully cutting up a chocolate bar into equal halves). It is mentally draining to constantly try and make sure you spend and do exactly equal.
Also remember that it is just your perspective that they favour the in-laws (especially at first). My parents constantly accused us of spending every weekend with the in-laws or having them babysit all the time, we hadn't seen them in months but my parents refused to believe what we said and just stewed in their anger.
You were petty and jealous, it would have been exhausting listening to your complaining that it wasn't exactly the same treatment as MIL after they did something nice for you. You're not a bad person, I think I would probably feel a little jealous in your situation but its important to not compare. Enjoy what your children do for you and don't compare. If you were always complaining and comparing then naturally your son would gravitate away from you.
It is true that living closer to one set of parents can mean that you are closer with them. We actually lived with my parents and then moved near them. My in-laws never once complained. We visited when we could but let's face it, it was impossible to give them equal time (or even close). My in-laws never complained or ruined things. They treated us so nicely and now we are way closer to them because they are always pleasant to be around. We are essentially no-contact with my parents due to jealousy and control (long story).
If you aren't sorry for your actions then I wouldn't seek him out. If you're genuinely sorry for being jealous then you definitely could send him some flowers with a note saying you miss them both and hope they are doing well. This would take swallowing your pride. I doubt he is going to reach out to you. From his perspective you brought drama and jealousy and possibly ruined his wedding?
Remember not to compare and try to suppress jealousy (not an easy thing to do). If you are a pleasant and happy person, then people will generally want to spend more time with you.
Bereavement wipes out everything


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