I would advise getting help from a priest, counsellor or community centre as the likelihood that you will be able to solve serious problems by yourself is not great. Both parties need to want to fix the problems or it cannot be done. Both parties will have to make some changes and compromises, plus put in a lot of time and effort. Self-help books can offer good advice and as you can read them on your own, they are non-threatening to the other party and can offer encouragement to you. You could look online for free books to download if money is a problem.
Serious marital problems include things like abuse and infidelity, but other problems in a relationship can also be serious, such as substance abuse or other addictions, perpetual lying and sexual problems. Most of the time, serious problems are hard to resolve on your own. That’s because people have behavior patterns that they go back to over and over, even if it’s damaging their marriage, simply because they don’t know how to change. It’s usually helpful in those cases to have an advocate or mediator who can help you talk through the issues. Professional counseling is a good option in this case.