I see you are hurting and grieving badly. So its understandable to be angry. When we fracture a bone or get badly wounded we have to rest the limb or not rub salt in that wound. So, if I were me I'd give you a break on meeting together with the teacher or having to encounter a hostile, cheating wife. You are going to be grieving for years by the Kübler-Ross model or otherwise. So, find a few good local friends and maybe a regular counselor who you can rely on for some help.
People will say all sorts of hurtful things and cliches. You'll hear a zillion things like the following: "You must have done something wrong". "No woman leaves a man who treats her right". "She doesn't want to be with you". "Do you want her back?". "What was your part in it?", etc. And none of this is going to make much sense or be of comfort to you at this point. Fact is your W has decided to destroy what's left of the marriage and family and you have to face the consequences! So, be gracious, give them a break, because like innocent children, they don't know better as they are not in your shoes so they cannot be of help or comfort so no use turning to them.
Let go? I'd go further and say aggressively and smartly protect your own interests. The woman is too far gone so do not entertain any hope she'll turn around - that would be a big mistake - leave that entirely to God. So, think 5 steps ahead and while the W is still rolling in the muck of an affair. Get the maximum child custody and property you can work towards keeping and look after the kids as best you can. The fact is the "no-fault" system has no moral standing. So you and your L have to get very busy and creative.
DBing? Do not let it lead you to foolishly hope that you can stop this thing. The lack of social and legal morality have already beaten you to it. There are the textbook DBing people you believe they have "succeeded" by their heroic "efforts" and reach out to be of help but that is probably not quite true as there are all kinds of factors and sitches. And there are the remaining lost souls. Either way its the blind leading the blind. And so you cannot rely on this either.
Catholic? Till death do you part? Then don't file D yourself, let the wayward W do it or you can file a "legal separation" if you have to or do the Dobson Choice thing. The Catholic church for all its might and where you probably got married is very weak against a wayward spouse, the established no-fault legal system and the morally decrepit society you live in. Pastors have little or no training or understanding of real life. People will assume all sorts of things; very few know exactly what their Church or Bible really says. So, pray directly to the Lord your God and find out for yourself.
