You say LTR -sounds like you have wisely avoided marriage. If so, very well done. You are safer than many in your predicament.

Women change when they have children. Its like a dormant circuits in the brain are activated and remain on for life. A fully mature woman woman is not the same as a childless woman. The problem is (if you have the wisdom to avoid used goods) you buy into a childless one and then roll the dice. After becoming a mother the way she sees the world and her priorities change. You meanwhile get effected a little by her pregnancy and nursing hormones and actually change your behaviour to become "more beta" as you put it. This is scientifically proven to be inevitable to some extent.

The problem is that as she comes into her mature female brain and into her power as a mother, if she changes in ways that are bad for you, it can cause a situation a little like the one where the frog is gradually boiled alive in water that very slowly gets hotter. You know you are not comfortable but you bought into this. You are a well intentioned and honourable man. Dumping the mother of your children is a "nuclear option" that may win you huge criticism from society -unless you have a magic get out of jail card like she was unfaithful -which will make your choice excusable. Its a lot easier to stay in case you make a big mistake and if she is the wrong woman for you, the water just keeps getting hotter but each increment it heats up, you still choose to stay.

So what to do? I have myself tried more than one solution over time. I have, after much agonising, dumped a cold bitch and been certain it was the best thing I ever did. I have soldiered on when my heart was not in it and that had consequences for the relationship that were not good. On the next occasion, I stuck with it and am presently pretty close to the end of serving a 20 year sentence for impregnation and considering my options. What I can say is that you will face a choice -lose your kids or become a massive slave to your ex, working constantly to please her, fit in with her and help her, just to get access to your kids. It makes it hard to have a life of your own and if she proves hard to work, losing your kids and starting over is the better option. (WOmen hold all the power over your kids once you split with them) I have done it. It hurts but life goes on. That's the options you have to weight, whether or not you have a get out of jail card for infidelity.

Condom smell -first off always assume a thing is what it looks like unless proven otherwise. I appreciate that there is a difficulty here in that when deciding whether to dump the mother of his children, a wise man naturally demands a high burden of proof. It may be very hard to obtain this but unless you can prove that she is innocent here, the smell added to her behaviour must count as very strong evidence towards dumping, even if you can't point to it as the actual nail in the coffin. Weight everything together if you can't disprove it. How does she normally behave when innocent? Most of us at first don't get what the other person is on about or that they take it seriously and this can look guilty but once we do get it, then we get quite up set when falsely accused and deny the accusation. The guilty (if inexperienced in deceit) tend to have more trouble in boldly declaring "That is a crock of shit".

I have minimal experience with condoms but latex has a unique smell. I asked AI and it seems that things other than latex can have a latex smell -things like synthetic rubber. The only possible thing I can think of might be a lycra containing underwear gusset on a sweaty day. But this should be replicable on any given sweaty day and it is also likely that her whole bottom would smell a bit latexy not just the vulva area.

I would also DNA test your kids whatever. DNA testing is cheap as chips, fun and tells you a lot. If you test the mother too you can even see if you have weaknesses that might combine badly (which could be a reason for starting over with someone else). If you fear her being a bitch over DNA testing, then yes, you probably do have a huge fidelity problem because at best she does not even know for certain if the kids are yours. Buy kits and get samples first (just in case she is obstructive), then tell her you want to do the testing. If she is cool with it, then great then just take more samples or fake doing so. If she is obstructive, that tells you something you need to know.

acted mostly alpha

Here we go.... This is going to be a shit show. Naw bro, you weren't alpha T all. You were "acting*. That's mistake 1

Then we got a baby

No got you decided to make a baby. This was your decision and now your responsibility to manage,. You're playing on hard mode. Did you treat your baby momma like she was a girlfriend? Did you game her? Sounds like that would be a no.

I probably got also beta and opened up too much with her.

Here we go again with this fucking autistic alpha bullshit. You don't understand it at all and this fucked you over. Here's the thing, you lived this woman enough to have a kid with her and you expect that acting like an unfeeling robot is going to be a problem? Start living in the real world.

I noticed clear condom smell down there..

For fucks sake! This is your fucking tell? How fucking retarded! Where is down there? The basement or did you dive strait into her pussy when she got home? Does this chick shower? If this is your only tell congrats, you're a paranoid moron.

Like complaining after sex

I guarantee you acted like you didn't trust her and gave her a shitty dicking. Women notice these things.

Then I confronted her and she started acting very guilty

No shit.. She was probably thrown off guard with this stupid shit. Especially if that was your only evidence. You handled this poorly.

Years went by and got another kid

It's official. You sir are a retard. Let's just get this straight: you think she's a cheater so you reward her with another kid?? Well wasn't that clever?

roast me for getting weak beta

Sounds like you have a submissive side. Ghey. You've asserted you were alpha. You never were and there is no such thing. Guys like you are so beyond help. You never should have found the red pill. You bought into a stupid alpha trope instead of understanding the tools everyone gave you. You also used none of them.

My advice is to look in the mirror and slap yourself hard for being a phaggot. Drop this phony alpha act. It's ruining your life Focus on being a good dad to your kids. Depending on the laws in your area you might be completely fucked as moms have all the power. And now as a father you broke the family dynamic. Raising kids properly is a big time investment. You gave yourself a lot less freedom to fuck up future relationships with your stupidity. You dig this hole not her. So don't start blaming your babymomma for your failings as a man. Own your shit.